Question

How to find the prime numbers between 1 to 100 in C++

Answer 1

#include <iostream>

int main(void) {
    int count; 

    for (int n = 2; n <= 100; n++) {
        count = 0;
        for (int i = 2; i <= n / 2; i++) {
  	        if (n % i == 0) {
     	        count++;
  	            break;
	        }
        }
    
        if (count == 0) {
	        std::cout << n << " ";
        }  
    }
  
    return 0;
}



/*
run:

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 

*/

 

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Answer 2

#include <iostream>
#include <cmath.h>

int isPrime(int n) {
    if (n < 2 || (n % 2 == 0 && n != 2)) {
        return 0;
    }
 
    int count = floor(sqrt(n));
    for (int i = 3; i <= count; i += 2) {
        if (n % i == 0) {
            return 0;
        }
    }
    return 1;
}

int main(void) {
    int count; 
 
    for (int n = 2; n <= 100; n++) {
        count = 0;
        for (int i = 2; i <= n / 2; i++) {
            if (n % i == 0) {
                count++;
                break;
            }
        }
     
        if (count == 0) {
            std::cout << n << " ";
        }  
    }
   
    return 0;
}
 
 
 
/*
run:
 
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 
 
*/

 

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