当我们用负参数调用Malloc时会发生什么? [英] what happens when we call Malloc with negative parameter?

问题描述

7.22.3.4 malloc函数malloc函数为一个对象分配空间，该对象的大小由size指定，其值是 不确定.

7.22.3.4 The malloc function The malloc function allocates space for an object whose size is specified by size and whose value is indeterminate.

原型:void *malloc(size_t size);

我尝试将负值作为参数传递:malloc(negative)返回NULL.

I tried passing a negative value as a parameter: malloc(negative) returns NULL.

是因为[size_t]负数转换为无符号的[某个大值]，并且无法分配所需的空间，还是函数检查参数返回了NULL?

Is it because the [size_t] negative converted to unsigned [some big value] and cannot allot required space or is the function checking parameter and returns NULL?

如果将其转换为大正值，则在调用malloc(INT_MIN+2)时仍返回NULL，但是分配给指针的malloc(0)和*p = somevalue起作用.那怎么办?

If its getting converted to big positive, then when calling malloc(INT_MIN+2) it still returns NULL, but malloc(0) alloted to pointer and *p = somevalue works. What about this?

实现定义了吗?

阅读此链接: malloc(0)

推荐答案

即使您将负值传递给malloc，size_t值也始终为正.负值将转换为类型为size_t的无符号值，这将导致巨大的正值.

A size_t value is always positive even if you pass a negative value to malloc. The negative value is converted to an unsigned value of type size_t which leads to a huge positive value.

示例:

char *p = malloc(-2);

等效于:

char *p = malloc(SIZE_MAX - 1);  // SIZE_MAX is the maximum
                                 // size_t value 

这篇关于当我们用负参数调用Malloc时会发生什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！