c - 变量在循环中途发生变化，我不知道是什么问题

Question

我正在编写一些代码来计算 GPA，当我开始一个循环时，我的一个变量“numClasses”在循环中途将值更改为一个巨大的数字，我无法弄清楚发生了什么。

#include <stdio.h>

int main()
{
  float crdtHrs[] = {}; //Credit hours for this term
  float numClasses; //Amount of classes taken this term
  float qltyPoints[] = {}; //Quality points for term
  float classes[] = {}; //Array for class grades

  printf("Please enter total number of classes -> ");
  scanf("%f", &numClasses);

  float a = numClasses; //using new variable because this way the loop works

  for(int i = 1; i <= a; i++)
  {
    printf("\nGPA class #%d -> ", i);
    scanf("%f", &classes[i - 1]);
    printf("Credit hours for course -> ");
    scanf("%f", &crdtHrs[i - 1]);
    printf("%f", numClasses); //at some point of my loop numClasses changes value
  }

  return(0);
}

Answer 1

不错的零长度数组缓冲区溢出。繁荣。让我们安排一下，稍后声明数组，这样我们就可以给它们指定大小。

  printf("Please enter total number of classes -> ");
  scanf("%f", &numClasses);
  int a = (int)numClasses;

  float crdtHrs[a]; //Credit hours for this term
  float qltyPoints[a]; //Quality points for term
  float classes[a]; //Array for class grades

现在我们以正确的大小在堆栈上分配数组。