算法竞赛入门经典 习题3-3乘积的末3位

#include <cstdio>
#include <cctype>
#include <cstring>
int main(){
	char ch = EOF;
	char in[500];
	char buf[500];
	memset(in, '\0', sizeof(in));
	memset(buf, '\0', sizeof(buf));

	int i = 0;
	while ((ch = getchar()) != '\n' && ch != EOF){
		in[i++] = ch;
		if (i >= 500){
			printf("overflow!\n");
			return 1;
		}
	}
	in[i] = '\0';
	char *tmp = in;
	int num = 0;
	int product = 1;
	while (*tmp != '\0'){
		if (isdigit(*tmp)){
			num = num * 10 + (*tmp - '0');
		}
		else if (isalpha(*tmp) || *tmp == ' '){
			if (num != 0){
				product *= num;
				product %= 1000;
				num = 0;
			}
		}
		++tmp;
	}
	if (num != 0){
		product *= num;
		product %= 1000;
		num = 0;
	}
	printf("product=%d\n", product);
	return 0;
}