This C Program calculates prime numbers in a given range. This program checks first if the number is prime number. Then prints the prime numbers till the given range.

Here is source code of the C program to calculate the prime numbers in a given range. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

`/*`

`* C program to find prime numbers in a given range.`

`* Also print the number of prime numbers.`

`*/`

`#include <stdio.h>`

`#include <stdlib.h>`

void main()

`{`

int num1, num2, i, j, flag, temp, count = 0;

printf("Enter the value of num1 and num2 \n");

scanf("%d %d", &num1, &num2);

if (num2 < 2)

`{`

printf("There are no primes upto %d\n", num2);

exit(0);

`}`

printf("Prime numbers are \n");

temp = num1;

if ( num1 % 2 == 0)

`{`

`num1++;`

`}`

for (i = num1; i <= num2; i = i + 2)

`{`

flag = 0;

for (j = 2; j <= i / 2; j++)

`{`

if ((i % j) == 0)

`{`

flag = 1;

break;

`}`

`}`

if (flag == 0)

`{`

printf("%d\n", i);

`count++;`

`}`

`}`

printf("Number of primes between %d & %d = %d\n", temp, num2, count);

`}`

$ cc pgm17.c $ a.out Enter the value of num1 and num2 70 85 Prime numbers are 71 73 79 83 Number of primes between 70 and 85 = 4

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If you wish to look at other example programs on Mathematical Functions, go to C Programming Examples on Mathematical Functions. If you wish to look at programming examples on all topics, go to C Programming Examples.