Learn to print all prime number between two given number in C language

In this article, you’ll learn how to print all prime number between two given number in C language without giving input from the keyboard or giving input from the keyboard.

Q: what is the prime number

Ans: A natural number which only divided by itself and 1 is called a prime number and you also say that a prime number is a natural number which is greater than 1 and cannot be formed by multiplying two natural number.

  • 1 is not a prime number.
  • 2 is the smallest prime number and only even prime number.
  • Example of prime number 2,3,5,7,11,13 etc.

To print all prime number between two given number we generally use the following steps:

  • First, we take two number then add 1 in the first number and subtract 1 in the second number to check prime number between two intervals number.
  • We use two for loop first, for loop for checking all number between the intervals and second for loop to check prime number.
  • If second for loop is true, then it means the number is not a prime number and increments the number check again
  • If second for loop is false, then it checks again
  • if(i==x) then it a prime number and check again for the first for loop.

Example 1: write a program in C language to print all prime number between two given number, without input from keyboard

#include <stdio.h>

#include <conio.h>

int main()

{

  int f1=1,f2=50,x,i;

  for(x=f1+1;x<=f2-1;x++){

       for(i=2;i<x;i++)

       if(x%i==0)

       break;

       if(i==x)

       printf(“%d “,x);

  }

  return 0;

}

 

The Output of this program:

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47

 

Example 2: write a program in C language to print all prime number between two given number, with input from the keyboard

 

Solution:

#include <stdio.h>

#include <conio.h>

int main()

{

  int f1,f2,x,i;

  printf(“Enter first number: “);

  scanf(“%d”,&f1);

  printf(“Enter second number: ” );

  scanf(“%d”,&f2);

  for(x=f1+1;x<=f2-1;x++){

       for(i=2;i<x;i++)

       if(x%i==0)

       break;

       if(i==x)

       printf(“%d “,x);

  }

  return 0;

}

 

The Output of this program:

Enter first number: 5

Enter second number: 100

7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

 

Example 3: write a program in C language to print all prime number including two given number, with input from keyboard Solution:

#include <stdio.h>

#include <conio.h>

int main()

{

  int f1,f2,x,i;

  printf(“Enter first number: “);

  scanf(“%d”,&f1);

  printf(“Enter second number: ” );

  scanf(“%d”,&f2);

  for(x=f1;x<=f2;x++){

       for(i=2;i<x;i++)

       if(x%i==0)

       break;

       if(i==x)

       printf(“%d “,x);

  }

  return 0;

}

 

The output of this program:

Enter first number: 2

Enter second number: 17

2 3 5 7 11 13 17

Program to check prime number in C language

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