为什么我的程序死在死循环里了？

Question

#include<stdio.h>
#include<stdlib.h>
int main()
{
    FILE *fp;
    float num[50];
    int i=0;

    if((fp=fopen("c:\\card.txt","w"))==NULL){
        printf("fail to open!\n");
        exit(0);
    }
    scanf("%f",&num[i]);
    while(num[i]!=-1){
        fprintf(fp,"%f ",num[i]);
        scanf("%f",&num[i]);
        i++;
    }
    fclose(fp);
    putchar('\n');
    return 0;
}
while语句那里

Answer 1

主要问题: 就是 i++ 的位置放错了,导致 num[i]!=-1 中的 num[i] 指向了随机值.

#include<stdio.h>
#include<stdlib.h>
int main() {
    FILE *fp;
    float num[50];
    int i = 0;

    if ((fp = fopen("c:\\card.txt", "w")) == NULL) {
        printf("fail to open!\n");
        exit(0);
    }
    scanf("%f", &num[i]);
    while (num[i] != -1) {
        fprintf(fp, "%f ", num[i]);
        i++;
        scanf("%f", &num[i]);
    }
    fclose(fp);
    putchar('\n');
    return 0;
}