#include <time.h> #include <stdio.h> #include <stdlib.h> int main(void) { int stage; int a, b, c; int x; int n; clock_t start, end; srand(time(NULL)); printf("input the result \n"); start = clock(); for (stage = 0; stage < 10; stage++) { a = 10 + rand() % 90; b = 10 + rand() % 90; c = 10 + rand() % 90; n = rand() % 17; printf("%d%*s+%*s%d%*s+%*s%d =", a, n, "", n, "", b, n, "", n, "", c); do { scanf("%d", &x); if (x == a + b + c) break; printf("\awrong,input again!"); } while (1); } end = clock(); printf("hello world\n", (double)(end - start) / CLOCKS_PER_SEC); return 0; } 