Welcome

$$ \text{Vitamin C Programming Supplement} $$

Welcome to Vitamin C Programming Supplement. It is a guide like book for programming beginners focusing on the C Programming Language. A lot of resources are available online, but we're here to make a compilation (gather necessary resources here) as well as exercises to enhance your programming skills.

We have tried to make this content easy as possible from a Bangladeshi point of view and written exams. Furthermore, we will be sharing our notes on Programming fundamentals and the C programming language.

It takes a lot of time to master a programming language. You need to put in practice and dedication to achieve proficiency. You can't just read books or watch tutorials; you have to write code yourself and try new things (explore!).

This book is prepared as a supplement to your mainstream learning resource (like YouTube playlists or any books). After completing topics from your main learning source, you can find additional information/knowledge and some practice problems here. Do not take this book as your main book to learn as we have skipped many essential topics believing that you will learn them in your class or YouTube lecture or from books.

Acknowledgement

"আমরা একাত্তর দেখিনি, কিন্তু চব্বিশ দেখেছি" (Bangla Phonetic:"Amra Ekattor Dekhini, Kintu Cobbish Dekhechi") "We haven't seen seventy-one, but have seen twenty-four"

We salute our heroes of 52's Language Movement, 71's Freedom Fighters, Honoured Leaders, 24's fearless activists, who fought bravely against autocratic government, and the martyrs of July Massacre.

Also, we extend our respect to our Structured Programming Course Coordinator for his sincere efforts in guiding us through this course. We dream a beautiful and better world too...

Start Here

Start with C (NOT PYTHON)

Why to learn such old fashioned language like C ?

• It is considered as the mother or backbone of all programming language
• If you have have a good understanding of solving problem with C to learn other programming language like C++, Java, JavaScript, Kotlin (Kotlin needs knowledge of JAVA), Rust, will be easy-peasy !
• Harvard Uni, BUET, almost every university starts Programming courses with C Programming language.
• Linux, Windows Kernel is written in C.
• Good to know: You have direct access to memory that most other languages doesn't. C is like a basic building blocks of everything. You can do everything in C.
• Since C doesn't have enriched library, you need to implement your bigger ideas manually thus having a good understanding over those concepts (like Sorting, Stack, Queue, etc.)
• Python lovers don't know what is happening inside. You can't call yourself a computer engineer if you don't know the mechanism. Let the python lovers and web developers make noise. Don't listen to them. Even, Python and Java BackEnd is written in C. Now, lets start Vitamin C.

Some of the Notes on C are given below: https://github.com/KaziRifatMorshed/WelcomeToProgramming

1. Editor and Compiler Setup

Considering you as newbies we are only going to suggest 2 editors (each) here. If you have any problems installing them then contact us. Until you've got some hands on experience it is better to stick with the first options in both cases.

i. Offline

We prefer to use VS Code and MSYS2 compiler.

ii. Online

Pros of Online IDE

• Easiest to use
• Clean and Beginner friendly User Interface

Cons of Online IDE

• Need active internet connection
• Can perform basic codes. Online IDEs do not allow file operations.
• Codes are not saved in cloud/remote computer. You can copy and paste the co

Summary: Avoid online IDE

iii. Android

???

Hello, check, check !

The typical first program to check whether compiler, IDE are working or not...

#include<stdio.h>

int main()
{
    printf("Hello World);
    return 0;
}

fun fact, it is a 7 line code, but same work can be done with only 2 lines of code!

#include<stdio.h>
int main(void){printf("Hello World");}

Write this code character by character in your favorite code editor and run. If everything is alright then you will see your computer welcoming you to the world of programming😉.

Learning Resources

A gentle reminder...
This book is prepared as a supplement to your mainstream learning resource (like Youtube Playlist or any Bangladeshi Book). After Completing topics from your main learning source, you can find additional knowledge and practice problems here. Do not take this book as your main book to learn as we have skipped many things believing that you will learn them in your class or youtube lecture.

Now let's get you started on your learning journey. Choose any of the following ones to start. If you love to read and you can understand well from reading then you may choose option 1. Otherwise choose the other options. (Those are videos. I'll suggest that you try both and then decide.)

How to Start C (Resources)

There are many resources !!!! I am panicked !!! How/Where to start ?
Don't skip CS50, this is a must !!! Select any one from above list as your mainstream learning. But your learning will not complete with one source. YOU HAVE TO EXPLORE OTHER RESOURCES too !!!!!!!!!!

More Resources:

• MIT OpenCourseWare
• https://nptel.ac.in

If you want to download a whole youtube playlist with subtitle, you can check this link.

Primary Knowledge

qwertyuiop

Helpful Tools

CPH extension

link: https://marketplace.visualstudio.com/items?itemName=DivyanshuAgrawal.competitive-programming-helper

Pros:

Online C visual debugger https://pythontutor.com/c.html

Pros:

• visualize variables and changes step by step

Cons/Limitations:

• Can not take input (You have to define values of variables within source code)
• Can not process long code (Suitable for অল্প পরিমাণ কোড and beginners)

Special Characters

Special characters like form-feed (and others) are non-printing characters that perform certain control functions in text processing. Here's a brief explanation of some of them, including form-feed:

1. Form-feed (\f)

• The form-feed character (\f) is used to signal the end of a page in printed documents. In the past, it would move the printer to the top of the next page.
• It's rarely used today but might still appear in some contexts (e.g., older printers, plain text files designed for page breaks).

Example:

text = "Page 1 content\fPage 2 content"
print(text)

In this case, \f represents a form-feed, which would traditionally move content to a new page.

2. Newline (\n)

• The newline character (\n) moves the cursor to the next line.
• It is widely used in modern text processing to mark line breaks.

Example:

text = "First line\nSecond line"
print(text)

3. Carriage Return (\r)

• The carriage return character (\r) moves the cursor to the beginning of the same line.
• In older systems (e.g., typewriters and early computers), \r would reset the cursor position to the start of the line without moving down.

Example:

text = "Hello\rWorld"
print(text)

This would print "World", as \r causes the cursor to return to the start of the line, overwriting "Hello".

4. Tab (\t)

• The tab character (\t) inserts horizontal spaces, usually equivalent to 4 or 8 spaces, depending on the environment.

Example:

text = "Column 1\tColumn 2\tColumn 3"
print(text)

5. Backspace (\b)

• The backspace character (\b) moves the cursor one position backward, which can effectively delete the previous character when printed.

Example:

text = "Hello\b World"
print(text)

This would print "Hell World" because the backspace removes the "o".

6. Null Character(\0)

Summary of Common Special Characters:

• \f – Form feed (new page).
• \n – Newline (new line).
• \r – Carriage return (return to the beginning of the line).
• \t – Tab (horizontal space).
• \b – Backspace (deletes the previous character).

Each of these special characters can be used for controlling text formatting in various contexts. Today, most of them are used primarily in text processing and formatting, especially in file or console output.

Data Types, Variables and Input Output

Learn

Although there are many data types in c, for now you only need to learn a few. These are int, float, double, char, long long int. You can learn more about them from the following resources.

Practice

Try to solve the following problems. If you face difficulties or this is your first time solving problem on an online platform please refer here at first. Then if you can't solve it after trying for some time you can see the solution. But try first. Otherwise it won't be beneficial for you.

Pre Processor

#define

typedef

Operator & Expression

Theory

Execute this line and think, what is happening...

#include <stdio.h>
int main(void) {
  int a, b, c, d, e;
  e = 7;
  printf("e = %d\n", e);
  c = d = e;
  printf("c = %d, d = %d, e =  %d\n", c, d, e);
  a = b = c = d = e = -3; // last "value" or "value of variable" (-3) is going to be assigned to all variables before the last one
  printf("%d %d %d %d %d ", a, b, c, d, e);
}

similarly,

#include <stdio.h>
int main(void) {
  int a = 1, b = 2, c = -3, d = 0, e = b, f = e;
  printf("%d %d %d %d %d %d", a, b, c, d, e, f);
}

You can assign multiple statements in one line with comma. Luckily, you wont have to write multiple lines with semicolon.

#include <stdio.h>
int main(void) {
  printf("Hello "), printf("World"), putchar('\n'), printf("input any int value:");
  int a = 0;
  scanf("%d", &a), printf("\na is %d...", a);
}

this trick is helpful for situation like:

// Note that, this is a cuda code, do not get confused it with a C Programming language code
// the purpose of presenting it is to let you know that you can use this trick in scenarios like this...

#include <cstdio>
#include <cstdlib>
#include <cuda.h>

#define SIZE 1024

__global__ void VectorAdd(int *a, int *b, int *c, int n) {
  int i = threadIdx.x;
  if (i < n) {
    c[i] = a[i] + b[i];
  }
}

/*
".cu": "cd $dir && nvcc $fileName -o $fileNameWithoutExt -arch=sm_86 &&
$dir$fileNameWithoutExt",
*/
int main(void) {
  int *a, *b, *c;
   
  cudaMallocManaged(&a, SIZE * sizeof(int)), cudaMallocManaged(&b, SIZE * sizeof(int)), cudaMallocManaged(&c, SIZE * sizeof(int));

  for (int i = 0; i < SIZE; i++) {
    a[i] = b[i] = i;
    c[i] = 0;
  }


  int threadsPerBlock = 256;
  int blocksPerGrid = (SIZE + threadsPerBlock - 1) / threadsPerBlock;

  // VectorAdd<<<1, SIZE>>>(a, b, c, SIZE); // <<<1, SIZE>>> WAS AN ERROR
  VectorAdd<<<blocksPerGrid, threadsPerBlock>>>(a, b, c, SIZE);

  // Kernel execution happens here

  cudaDeviceSynchronize(); // Wait for kernel to finish

  for (int i = 0; i < 10; i++) {
    printf("c[%d] = %d\n", i, c[i]);
  }

  cudaFree(a), cudaFree(b), cudaFree(c);

} // WORKING

Problems

• Click on the title of the problem to submit your solution before looking at our solution.
• We discourage looking at our solution before attempting to solve it by yourself first.

1. Simple Calculator ↗️

   Given two numbers X and Y. Print the summation and multiplication and subtraction of these 2 numbers.

   Input

   Only one line containing two separated numbers \(X, Y (1  ≤  X, Y  ≤  10 ^ 5)\)

   Output

   Print 3 lines that contain the following in the same order:

   1. "\(X + Y =\) summation result" without quotes.
   2. "\(X * Y =\) multiplication result" without quotes.
   3. "\(X - Y =\) subtraction result" without quotes.

   Examples

   Input

   5 10
   

   Output

   5 + 10 = 15
   5 * 10 = 50
   5 - 10 = -5
   

   Notes

   Be careful with spaces.

   Hint:

   Press the eye icon to reveal hint.
    Use long long int instead of int
    Don't forget to use the designated format specifier for long long int (%lld)
   

   Solution

   // Press the eye icon to reveal solution.
   #include <stdio.h>
   
   int main()
   {
       long long x, y;
   
       scanf("%lld %lld", &x, &y);
   
       printf("%lld + %lld = %lld\n", x, y, x + y);
       printf("%lld * %lld = %lld\n", x, y, x * y);
       printf("%lld - %lld = %lld\n", x, y, x - y);
   
       return 0;
   }
   

2. Difference ↗️

   Hint:

   Press the eye icon to reveal hint.
    Use long long int instead of int
    Don't forget to use the designated format specifier for long long int (%lld)
   

   Solution

   // Press the eye icon to reveal solution.
   #include <stdio.h>
   
   int main()
   {
       long long a, b, c, d, x;
   
       scanf("%lld %lld %lld %lld", &a, &b, &c, &d);
   
       x = (a * b) - (c * d);
   
       printf("Difference = %lld\n", x);
   
       return 0;
   }
   

Precedence of Arithmetic Operators

Decision Making

if-else

if-else if-else

Ternary Operator

switch case

Looping

Practice problems with loop

Array

String

Practice problems on String

Practice problems on String with Library Functions

Scope

Loops again!

A gentle reminder

Structure & Union

typedef struct

Do not get confused

In C and C++, two different operators are used for calling methods: you use . if you’re calling a method on the object directly and -> if you’re calling the method on a pointer to the object and need to dereference the pointer first.
In other words, if object is a pointer, object->something() is similar to (*object).something().

Function

Practice problems with loop

Static variable & Static function

Pointers

Pointer arithmetic

Pointer passing to function

Intro to Algorithm

Time and space complexity - basic knowledge

It is better to have low time complexity and space complexity. But in many cases, we have to choose either one to solve our problem. Sacrificing one rather achieving both goal (goal of making minimum TC and SC) may be necessary but don’t worry that much now as a beginner. Focus on your logic building and Approach of solving problems.

Binary Search

Recursion

PRACTICE Recursion

Some of the following problems are directly copied from Zobayer Hasan vai's blog post on recursion. We are grateful to his open contributions towards learning CS.
You can use the Competitive Programming Helper (cph) extension in VS code to make your practice easier though it wont make a big difference.

ALL THE BEST FOR YOUR HARD WORK.

Problems on Recursion

1. Print 1 to 50 with a recursive function.\

   Output:

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 
   

   Hint:

            // recursive call
            printer(number + 1); // value of number increments here
   

   Solution:

    #include <stdio.h> 
    void printer(int number) {
        // printf("in this recursive call, number is %d \n", number);
        // Base Case
        if (number > 50) { // in a new recursive call, if the value of number is greater than 50, recursive call should terminate
            return;
        } else {
            printf("%d ", number);
            // recursive call
            printer(number + 1); // value of number increments here
        }
    }
    int main(void) {
        printer(1);
    }
   

2. Print 1 to 50 reversely with a recursive function.\

   Output:

   50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 
   

   Hint:

        uno reverse...
        write down only 5 recursive call (with code and variable value) in your notebook
   

   Solution:

    #include <stdio.h> 
    void printer(int number) {
        if (number > 50) { 
            return;
        } else {
            printer(number + 1); // notice the change here
            printf("%d ", number); // and think, how ?
        }
    }
    int main(void) {
        printer(1);
    }
   

3. Print out the series $$ 1 + 2 + 3 + ... + n $$ and determine the sum.
   Input:

   5
   

   Output:

   1 + 2 + 3 + 4 + 5 = 15
   

   Hint:

   #include <stdio.h>
    int sum_it(int num, int limit) {
    if (num > limit) {
        printf("= ");
        return 0;
    } else {
        printf("%d ", num);
        if (num != limit) {
        printf("+ ");
        }
        return num + sum_it(num + 1, limit);
    }
    }
    int main(void) {
    int limit = 0;
    scanf("%d", &limit);
    int sum = sum_it(1, limit);
    printf("%d", sum);
    } // done
   

4. You will be given an array of integers. Write a recursive solution to print it in (inputted) order.
   Input:

   5
   69 87 45 21 47
   

   Output:

   69 87 45 21 47
   

   Hint:

5. Same as before. Add index number (starting from 1) to each int output in (inputted) order.
   Input:

   5
   69 87 45 21 47
   

   Output:

   1.69 2.87 3.45 4.21 5.47
   

6. Same as before. Add index number (starting from n) to each int and get output in reverse order.
   Input:

   7
   69 87 45 21 47 76 2
   

   Output:

   7.69 6.87 5.45 4.21 3.47 2.76 1.2 
   

7. You will be given an array of integers. Write a recursive solution to print it in reverse order. Input:

   5
   62 87 45 24 47
   

   Output:

   47 24 45 87 62
   

8. Same as before. The program will print inputted numbers except even integers. Input:

   5
   62 87 45 24 47
   

   Output:

   47 45 87
   

9. Use recursion to find max among 2 integers.

10. Use recursion to find the max among 3 integers.

11. Use recursion to find min among 2 integers.

12. Use recursion to find min among 3 integers.

13. Write a recursive function to print an array in the following order.

    [0] [n-1] 
    [1] [n-2]  
    ... 
    [(n-1)/2] [n/2]
    

    Input:

    5
    1 5 7 8 9
    

    Output:

    1 9
    5 8
    7 7
    

14. Write a recursive program to remove all odd integers from an array. You must not use any extra array or print anything in the function. Just read the input, call the recursive function, and then print the array in main().
    Input:

    6
    1 54 88 6 55 7
    

    Output:

    54 88 6
    

15. Write a recursive solution to print the polynomial series for any input n: $$ 1 + x + x^2 + ... + x^{n-1} $$
    Input:

    5
    

    Output:

    1 + x + x^2 + x^3 + x^4
    

16. Write a recursive solution to evaluate the previous polynomial for any given x and n. Like, when x=2 and n=5, we have $$ 1 + x + x^2 + ... + x^{n-1} = 31 $$
    Input: 2 5 Output: 31

17. Write a recursive program to compute n!
    Input: 5 Output: 120

18. Write a recursive program to compute the n-th Fibonacci number. 1st and 2nd Fibonacci numbers are 1, 1.
    Input: 6 Output: 8

19. Write a recursive program to determine whether a given integer is prime or not.
    Input: 49 999983 1 Output: not prime prime not prime

20. Write a recursive function that finds the gcd of two non-negative integers.
    Input: 25 8895 Output: 5

21. Write a recursive solution to compute the LCM of two integers. You must not use the formula lcm(a,b) = (a x b) / gcd(a,b); find lcm from scratch...
    Input: 23 488 Output: 11224

22. Suppose you are given an array of integers in an arbitrary order. Write a recursive solution to find the maximum element from the array.
    Input: 5 7 4 9 6 2 Output: 9

23. Write a recursive solution to find the second maximum number from a given set of integers.
    Input: 5 5 8 7 9 3 Output: 8

24. Implement linear search recursively, i.e. given an array of integers, find a specific value from it. Input format: first n, the number of elements. Then n integers. Then, q, the number of queries, then q integers. Output format: for each of the q integers, print its index (within 0 to n-1) in the array or print 'not found', whichever is appropriate.
    Input: 5 2 9 4 7 6 2 5 9 Output: not found 1

25. Implement binary search recursively, i.e. given an array of sorted integers, find a query integer from it. Input format: first n, the number of elements. Then n integers. Then, q, the number of queries, then q integers. Output format: for each of the q integers, print its index (within 0 to n-1) in the array or print 'not found', whichever is appropriate.
    Input: 5 1 2 3 4 5 2 3 -5 Output: 2 not found

26. Write a recursive solution to get the reverse of a given integer. The function must return an int.
    Input: 123405 Output: 504321

27. Read a string from keyboard and print it in reversed order. You must not use any array to store the characters. Write a recursive solutions to solve this problem.
    Input: helloo Output: oolleh

28. Write a recursive program that determines whether a given sentence is palindromic or not just considering the alpha-numeric characters ('a'-'z'), ('A'-'Z'), ('0'-'9').
    
    Input:

    madam
    

    Output:

    palindromic
    

    Input:

    hulala
    

    Output:

    not palindromic
    

29. Implement prime number determining algorithm recursively.

    Hint:

    isPrime(num, j + 2);
    

    Solution:

        int isPrime(int num, int j) { // RECURSIVE
          if (num <= 1) {
            return false;
          }
          if (num % 2 == 0) {
            return false;
          }
          if (num % j == 0) {
            return false;
          }
          if (j * j <= num) {
            isPrime(num, j + 2);
          }
          return true;
        }
    

30. Implement strcat(), stracpy(), strcmp() and strlen() recursively.
    
    Input: test on your own
    Output: test on your own

31. If you already solved the problem for finding the nth fibonacci number, then you must have a clear vision on how the program flow works. So now, in this problem, print the values of your fibonacci function in pre-order, in-order and post-order traversal. For example, when n = 5, your program calls 3 and 4 from it, from the call of 3, your program calls 1 and 2 again....... here is the picture: Input:

    5
    

    Output:

    Inorder: 1 3 2 5 2 4 1 3 2
    Preorder: 5 3 1 2 4 2 3 1 2
    Postorder: 1 2 3 2 1 2 3 4 5
    

32. Convert a Decimal number to Binary.
    Hint:

    return Decimal_to_Binary_RECURSIVE(i / 2) ... ;
    

    Solution:

    #include <stdio.h>
    int Decimal_to_Binary_RECURSIVE(int i) {
        if (i == 0){
            return 0;
        }
        return Decimal_to_Binary_RECURSIVE(i / 2) * 10 + i % 2;
    }
    int main(void) {
        int i = 0;
        scanf("%d", &i);
        printf("the binary of the decimal num %d is %d", i, Decimal_to_Binary_RECURSIVE(i));
    }
    

33. All of you have seen the tower of Hanoi. You have 3 pillars 'a', 'b' and 'c', and you need transfer all disks from one pillar to another. Conditions are, only one disk at a time is movable, and you can never place a larger disk over a smaller one. Write a recursive solution to print the moves that simulates the task, a -> b means move the topmost of tower a to tower b.
    
    Input:

    3
    

    Output:

    a -> c
    a -> b
    c -> b
    a -> c
    b -> a
    b -> c
    a -> c
    x
    

Dynamic Memory Allocation

More on Memory

Linked List

Prerequisites:

Structure(must), Typedef, Pointers (must), Memory, importance of data type, stack and heap region of memory, dynamic memory allocation(malloc) and how it works.

Practice Problem

1. Problem: You will be given an array of integers. Use malloc() to allocate memory in the heap. Write a recursive solution to print them in (inputted) order. ??????????????

Input:

5
69 87 45 21 47

Output:

69 87 45 21 47

int main(int argc, char *argv[])

File Operations

Notes on File Operation with C

notes and tricks

• scanf("%[^EOF]",str); read full file at once
• freopen("fileout.txt", "w", stdout); directly save into the file (steam bypass)
• fprintf() e W+ dile full file override hoy, r+ thakle shudhu oi position er char gulo
• fscanf(): format %c ar %s er upor depend kore kivabe source theke ek ek kore collect korbe. jodi %s use kori then: ek ekta word by word catch kore, so, _buff (steam) e ekta ekta kore word dhukse, without counting whitespace characters, so, while loop er vitore amake printf() er vitore ekta space ditei hosse Jemon silo temon paite hole fscanf er vitore C ar printf er vitore S.
• int temp = 0; while (fscanf(f_input, "%d", &temp) != EOF) {
• while (fscanf(ptr, "%c", &str[i]) != EOF && i < 199) { i++;}
• while((ptr=strstr(str,word))!=NULL) {memmove(ptr,ptr+len,strlen(ptr+len)+1);}

Practice Problems

These problems are directly taken from https://github.com/joydeb1729/File_Practice_C. For solutions, please visit this github repo. You will find solutions in respective folder.

@main_author : Durjay1729
Github: https://github.com/joydeb1729/

1. Write a C program to read numbers from a file and write even, odd and prime numbers to three separate file.

input->

73771782	81296771	79982326	75332246	10128193
81643413	76259734	94432076	50063976	91748657
42311916	-1920042	90747362	53851612	43498487
73193311	96685173	39019033	8630045		59322952

Output->

even.txt

73771782
79982326
75332246
76259734
94432076
50063976
42311916
-1920042
90747362
53851612
59322952
59322952

odd.txt

81296771
81643413
91748657
43498487
96685173
8630045

prime.txt

10128193
73193311
39019033

2. Write a C program to compare two files.

input -> File1.txt

Learn C programming at KU.
Working with files and directories.

File2.txt ->

Learn C programming at KU.
Working with chatgpt and copilot.

Output->

Files are not equal.
Line: 2, column: 14

3. Write a C program to copy contents from one file to another file.

Hint with Solution:

#include <stdio.h>
#include <stdlib.h>

int main(void) {

  FILE *f1 = fopen("file3_1.txt", "r"), *f2 = fopen("file3_2.txt", "w");
  if (f1 == NULL || f2 == NULL) {
    printf("ERROR OPENING FILE");
    exit(EXIT_FAILURE);
  }

  char c1;
  while (1) {
    c1 = fgetc(f1);
    fputc(c1, f2); // focus
    if (c1 == EOF) { // EOF has been written to f2 and now loop needs to be stopped
      break;
    }
  }

  fclose(f1), fclose(f2);
} // DONE

4. Write a C program to count characters, words and lines in a text file.

input->

I love   programming.
Working   with files in C programming is fun.
I am learning  C  programming   at KU.

Output->

Total characters = 106
Total words      = 18
Total lines      = 3

5. Write a C program to remove a word from text file.

file.txt

I love programming.
Programming with MM Sir is fun.
Learning C programming at KU is simple and easy.

Take input from user.

6. Write a C program to remove specific line from a text file.

file.txt

I love programming.
Programming with MM Sir fun.
Learning C programming at KU is simple and easy.

take input from User

7. Write a C program to remove empty lines from a text file.

file.txt

I love programming.



Programming with files  fun.

Learning C programming at Codeforwin  simple and easy.

8. Write a C program to find and replace a word in a text file.

file.txt

I love programming.
Programming with files is fun.
Learning C programming at KU is simple and easy.

replace "file" with "chatgpt"

9. Write a C program to count occurrences of all words in a text file.

file.txt

I love programming.
Programming with files is so fun.
Learning C programming at KU is so simple and easy.

take input from User

10. Write a C program to convert uppercase to lowercase character and vice versa in a text file.

file.txt

I love programming.
---------PROGRAMMING IN C---------
Learning C programming at KU is simple and easy.

output->

i LOVE PROGRAMMING.
---------programming in c---------
lEARNING c PROGRAMMING AT ku IS SIMPLE AND EASY.

NOTE: the following four questions are previous lab test questions set by Dr Manishankar Mondal Sir on Strings. We have modified them to introduce file handling concepts.

11. Write a program that takes a file containing string with spaces from the user. Your program will then determine the following and save them in txt files.

1. Find the individual words and store them in a two-dimensional array. Save the words.
2. Count the number of vowels in each word. Save the counts for all words in a file.
3. Print the appearance counts of the distinct words? Draw a histogram considering the appearance counts and save them in another file.

Sample Input file input.txt:

I know the man. the man is a good human being. the man has good characteristics. man man man man  the the the the good good

First Output file:

I, vowel count = 1
know, vowel count = 1
the, vowel count = 1
man, vowel count = 1
the, vowel count = 1
man, vowel count = 1
is, vowel count = 1
a, vowel count = 1
good, vowel count = 2
human, vowel count = 2
being, vowel count = 2
the, vowel count = 1
man, vowel count = 1
has, vowel count = 1
good, vowel count = 2
characteristics, vowel count = 5
man, vowel count = 1
man, vowel count = 1
man, vowel count = 1
man, vowel count = 1
the, vowel count = 1
the, vowel count = 1
the, vowel count = 1
the, vowel count = 1
good, vowel count = 2
good, vowel count = 2

Second output file distinct_words_appearance_counts.txt:

I: *
know: *
the: ***
man: ***
is: *
a: *
good: ****
human: *
being: *
has: *
characteristics: *

12. Assume that you have an array of 20 positive integers in a file. Write a program to RECURSIVELY determine the SUMMATION of all prime integers in the array. You SHOULD write the prime testing function recursively. The array will be taken as input from file and append the answer to the input file at last.

input.txt

4
345
45
78
324
5
45
453
435
37
78
423
453
34
578
31
374
19
11
111

output:

4
345
45
78
324
5
45
453
435
37
78
423
453
34
578
31
374
19
11
111
sum:103

13. Write a program to take a string with spaces from a file. Your program will save the string to output.txt after trimming it. Let us assume that the input string is " I live in a beautiful village. ". Your program will remove the spaces from the front and back of the string and then save it. Thus, the output will be "I live in a beautiful village." For trimming (i.e., for removing spaces from the front and back) you need to create a user-defined function called "trimstring" that takes a string as a parameter.

14. "LTrim", "RTrim", and "MTrim", and "CountOccurrence"

Write a program that will take a string with spaces from file as input. Write four functions named "LTrim", "RTrim", and "MTrim", and "CountOccurrence". Each of these functions will take a string as a parameter.

"LTrim" will delete all the spaces from the left hand side of the parameter string and will return the string that will be obtained after deleting the left side spaces.

"RTrim" will delete all the spaces from the right hand side of the parameter string and will return the string that will be obtained after deleting the right side spaces.

"MTrim" will keep only one space between every two consecutive words. There can be multiple spaces between two words in a string. Only one space will be kept and other spaces will be deleted.

And, "CountOccurrence" will recursively count the occurrences of "abc" in a parameter string and will return the count. This function might also take other parameters as you wish to accomplish the task.

Contributions

Back Story, Our Motivations

During our 1st year 2nd term, me along with my close 3 friends felt necessity of collaboration and assistance to start programming life for beginners. We decided to help our

After our term final examination, during Eid Vacation, my friend, Ibnul Abrar Shahriar Seam sent me a link https://structured-programming-ku-cse.blogspot.com/ and added me as a contributor. Later, my classmates Azmain Inquaid Haque, and Joydeb Gan Prokas (Durjay) directly contributed to this book.

Later, a lot happened, we achieved the 2nd independence of Bangladesh on "36th July 2024" (05 August 2024) with the heroic patriotism of Abu Sayed Vai, Mir Mugdha Vai, and many more which motivated us to share our knowledge and thoughts to build this nation. To make it freely available for everyone and everyone's contribution, we decided to make it open by hosting in Github with mdBook.

We look forward to rebuild our motherland as well as making this world better.

...

The End