realloc 中的无效指针

Question

这个错误以前从来没有出现过，我不明白为什么会这样。我正在创建一个 C 程序来创建一个数组，然后重新分配它以添加更多元素。我在同一个程序中应用了很多不必要的概念来浓缩一些知识。

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

  // ALWAYS when doing a definition of new elements in a arrays, NEVER use size as a parameter
  // because if you assign one element as one, it will reset the value of size then reseting 
  // size < sizenew.
  // Ex: Do not do:
  //
  // for (size; size < newsize; size++) scanf ("%hu", &size)
  //
  // the number you choose for scanf will affect the number of times the loop will do, because size
  // is a parameter of while 
 

int main()
{
  _Bool decision;
  int* array;
  unsigned short size, newelements, oldsize, add, minus_oldsize, newsize, i, j;

  printf("Hello! put the size of the initial int array!\n");
  scanf("%hu", &size);
  
  array = malloc(size * 4);

  printf("Put the array elements one by one\n");
  for (i = 0; i < size; i++) scanf("%d", array + i);

  printf("This is your array:\n");
  for (j = 0; j < size; j++) printf("%d\n", *(array + j));

  printf("Do you want to add more elements? no(0) yes(1)\n");
  scanf("%d", &decision);
  if (decision != 1) return -1;

  printf("How many elements you want to add?\n");
  scanf("%d", &newelements);
  newsize = size + newelements;

  array = realloc(array, newsize * 4);

  free(array);
  
  return 0;
}

错误： realloc(): invalid pointer

Answer 1

看来问题出在对 _Bool

类型对象的 scanf 调用

_Bool decision;

//...

scanf("%d", &decision);

遗憾的是，_Bool 类型的对象没有可以安全地用于 scanf.

调用的转换说明符

相反，您可以使用 int.

类型的对象

另一个问题是在此调用中使用了不正确的转换说明符

scanf("%d", &newelements);

你的意思好像是

scanf("%hu", &newelements);

realloc 中的无效指针

invalid pointer in realloc

c

pointers

scanf

undefined-behavior

realloc