c语言中将函数指针作为形参_在C中将有效指针作为NULL指针

c语言中将函数指针作为形参

Prerequisite:An Example of Null pointer in C

先决条件：C中的空指针示例

Any pointer that contains a valid memory address can be made as aNULL pointerby assigning0.

通过分配0，可以将包含有效内存地址的任何指针设置为NULL指针。

Example:

例：

Here, firstly ptr is initialized by the address of num, so it is not a NULL pointer, after that, we are assigning0to the ptr, and then it will become a NULL pointer.

在这里，首先ptr由num的地址初始化，因此它不是NULL指针，此后，我们为ptr分配0，然后它将成为NULL指针。

Program:

程序：

#include <stdio.h>int main(void) {int num = 10;int *ptr = &num;//we can also check with 0 instesd of NULL if(ptr == NULL)printf("ptr: NULL\n");elseprintf("ptr: NOT NULL\n");//assigning 0 ptr = 0;if(ptr == NULL)printf("ptr: NULL\n");elseprintf("ptr: NOT NULL\n");return 0;}

Output

输出量

ptr: NOT NULLptr: NULL

翻译自: /c-programs/making-a-valid-pointer-as-null-pointer-in-c.aspx

c语言中将函数指针作为形参