c programming examples

Example 1 - C hello world program
/* A very simple c program printing a string on screen*/

#include<stdio.h>
 
main()
{
    printf("Hello World\n");
    return 0;
}

Output of above program:
"Hello World" Example 2 - c program to take input from user using scanf

#include<stdio.h>
 
main()
{
   int number;
 
   printf("Enter a number\n");
   scanf("%d",&number);
 
   printf("Number entered by you is %d\n", number);
 
   return 0;
}

Output:
Enter a number
5
Number entered by you is 5 Example 3 - using if else control instructions

#include<stdio.h>
 
main()
{
   int x = 1;
 
   if ( x == 1 )
      printf("x is equal to one.\n");
   else
      printf("For comparison use == as = is the assignment operator.\n");
 
   return 0;
}

Output:
x is equal to one. Example 4 - loop example

#include<stdio.h>
 
main()
{
   int value = 1;
 
   while(value<=3)
   {
      printf("Value is %d\n", value);
      value++;
   }
 
   return 0;
}

Output:
Value is 1
Value is 2
Value is 3
Example 5 - c program for prime number

#include<stdio.h>
 
main()
{
   int n, c;
 
   printf("Enter a number\n");
   scanf("%d", &n);
 
   if ( n == 2 )
      printf("Prime number.\n");
   else
   {
       for ( c = 3 ; c <= n - 1 ; c++ )
       {
           if ( n % c == 0 )
              break;
       }
       if ( c != n )
          printf("Not prime.\n");
       else
          printf("Prime number.\n");
   }
   return 0;
}

Example 6 - command line arguments

#include<stdio.h>
 
main(int argc, char *argv[])
{
   int c;
 
   printf("Number of command line arguments passed: %d\n", argc);
 
   for ( c = 0 ; c < argc ; c++)
      printf("%d. Command line argument passed is %s\n", c+1, argv[c]);
 
   return 0;
}

Above c program prints the number and all arguments which are passed to it. Example 7 - Array program

#include<stdio.h>
 
main() 
{
    int array[100], n, c;
 
    printf("Enter the number of elements in array\n");
    scanf("%d", &n);
 
    printf("Enter %d elements\n", n);
 
    for ( c = 0 ; c < n ; c++ ) 
        scanf("%d", &array[c]);
 
    printf("Array elements entered bu you are:\n");
 
    for ( c = 0 ; c < n ; c++ ) 
        printf("array[%d] = %d\n", c, array[c]);
 
    return 0;
}

Example 8 - function program

#include<stdio.h>
 
void my_function();
 
main()
{
   printf("Main function.\n");
 
   my_function();
 
   printf("Back in function main.\n");
 
   return 0;
}
 
void my_function()
{
   printf("Welcome to my function. Feel at home.\n");
}

Example 9 - Using comments in a program

#include<stdio.h>
 
main()
{
   // Single line comment in c source code
 
   printf("Writing comments is very useful.\n");
 
   /*
    * Multiline comment syntax
    * Comments help us to understand code later easily.
    * Will you write comments while developing programs ?
    */
 
   printf("Good luck\n"); 
 
   return 0;
}

Example 10 - using structures in c programming

#include<stdio.h>
 
struct programming
{
    float constant;
    char *pointer;
};
 
main()
{
   struct programming variable;
   char string[] = "Programming in Software Development.";
 
 
   variable.constant = 1.23;
   variable.pointer = string;
 
   printf("%f\n", variable.constant);
   printf("%s\n", variable.pointer);
 
   return 0;
}

Example 11 - c program for fibonacci series

#include<stdio.h>
#include<conio.h>
 
main()
{
   int n, first = 0, second = 1, next, c;
 
   printf("Enter the number of terms ");
   scanf("%d",&n);
 
   printf("First %d terms of fibonacci series are :-\n",n);
 
   for ( c = 0 ; c < n ; c++ )
   {
      if ( c <= 1 )
         next = c;
      else
      {
         next = first + second;
         first = second;
         second = next;
      }
      printf("%d\n",next);
   }
 
   getch();
   return 0;
}

Example 12 - c graphics programming

#include <graphics.h>
#include<conio.h>
 
main()
{
    int gd = DETECT, gm;
 
    initgraph(&gd, &gm,"C:\\TC\\BGI");
 
    outtextxy(10,20, "Graphics source code example.");
 
    circle(200, 200, 50);
 
    setcolor(BLUE);
 
    line(350, 250, 450, 50);
 
    getch();
    closegraph( );
    return 0;
}

For gcc compiler users

If you are using gcc compiler on linux operating system then you need to modify programs. For example consider the following programs which prints first ten natural numbers

#include<stdio.h>
#include<conio.h>
 
main()
{
    int c;
 
    for ( c = 1 ; c <= 10 ; c++ )
        printf("%d\n", c);
 
    getch();
    return 0;
}

Above source code includes a header file <conio.h> and uses function getch, but this file is Borland specific so it works in turbo c compiler but not in gcc. So the code for gcc should be like

#include<stdio.h>
 
main()
{
    int c;
 
    /* for loop */
 
    for ( c = 1 ; c <= 10 ; c++ )
        printf("%d\n", c);
 
    return 0;
}

If using gcc compiler save the code in a file say numbers.c, to compile the program open the terminal and enter command gcc numbers.c, this will compile the program and to execute the program enter command ./a.out .

Posted in: C