/* 判断是否为素数 */ |
#include <stdio.h> |
#include <math.h> |
int input_data( void ) { |
int data = 0; |
do { |
printf ( "Please input a positive integer:" ); |
scanf ( "%d" , &data); |
} while (data <= 0); |
return data; |
} |
int is_prime( const int data) { |
int i = 0; |
int max = sqrt (data); |
for (i = 2; i <= max; ++i) { |
if (data % i == 0) |
return -1; |
} |
return 0; |
} |
int main( void ) { |
int data = 0; |
int flag = 0; |
/* 输入一个正整数 */ |
data = input_data(); |
/* 判断是否为素数 */ |
flag = is_prime(data); |
if (0 == flag) { |
printf ( "%d is a prime number.\n" , data); |
} else { |
printf ( "%d is not a prime number.\n" , data); |
} |
return 0; |
} |