wap in c to find first 20 prime number

Sure, here is a simple C program to print the first 20 prime numbers:

#include <stdio.h>

int main() {
    int i, j, count, flag;

    printf("First 20 prime numbers are:\n");

    // 2 is the first prime number
    printf("2\n");
    count = 1; // count of prime numbers
    i = 3; // next number to be checked

    while (count < 20) {
        flag = 0;

        // check divisibility of i from 2 to i/2
        for (j = 2; j <= i/2; j++) {
            if (i % j == 0) {
                flag = 1;
                break;
            }
        }

        // if i is a prime number
        if (flag == 0) {
            printf("%d\n", i);
            count++;
        }

        // check next number
        i++;
    }

    return 0;
}

This program uses a while loop to find the first 20 prime numbers. It starts from 2 (the first prime number), and for each subsequent number, it checks whether the number is divisible by any number from 2 to the number divided by 2. If the number is not divisible by any of these numbers, it is a prime number, and the program prints it and increments the count of prime numbers. The loop continues until it finds 20 prime numbers.