Prime Number Program in C

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Prime Number Program in C

Vinay Khatri
Last updated on August 28, 2022

    Here we will write a code in C language to check whether the entered number is a prime number or not. Here is a sample code of the Prime Number Program in C.

    What is a Prime number?

    A natural number will be called a prime number if it is only divisible by 1 and itself. For example, 3 is a prime number because it is only divisible by 1 and itself.

    Steps

    • First, we ask the user to enter a number
    • Then we create a loop from 2 to half of that number.
    • Inside the loop using the if statement we will check whether the entered number is divisible by any of number between 2 to half of the entered number.
    • If the number is divisible by any of number between 2 to half of the entered number, we will break the loop and print the statement that the entered number is not a prime number.

    Statements used

    • for loop
    • break statement
    • % (modules)
    • if…..else

    Prime Number Program in C

    #include<stdio.h>
    #include<conio.h>
    void main()
    {
    int num, i;
    clrscr();
    printf("Enter a number:");
    scanf("%d",&num);
    if(num==1 ||num==2)
        printf("It is a Prime Number");
    else{
        for(i =2;i<=num/2;i++)
                    {
                    if(num%i==0)    //check whether num is divisible by i or not
                     {  printf("It is not a Prime Number");
                        break;
                      }
                    else
                        if(i==num/2)
                          printf("It is a prime number ");
                     }
         }
     getch();
    }

    Output:

    Enter a number:49
    It is not a Prime Number

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