#include <stdio.h>
#include <math.h>

int prime(int p);
int PrimeSum(int m, int n);

int main()
{
    int m, n, p;

    scanf("%d %d", &m, &n);
    printf("Sum of ( ");
    for (p = m; p <= n; p++) {
        if (prime(p) != 0)
            printf("%d ", p);
    }
    printf(") = %d\n", PrimeSum(m, n));

    system("pause");
    return 0;
}

/* 你的代码将被嵌在这里 */
int prime(int p) {
    if (p <= 0 || p == 1)
        return 0;
    if (p == 2)
        return 1;
    for (int i = 2; i * i <= p; i++)
        if (p % i == 0)
            return 0;
    return 1;

}

int PrimeSum(int m, int n) {
    int sum = 0;
    for (int i = m; i <= n; i++)
        if (prime(i) == 1)
            sum += i;
    return sum;
}

判断是否是素数的函数非常重要。