你将如何释放分配的内存？

I need to free some memory allocated on my program. Can I use something to clean the memory when I need it ?

我需要释放一些在程序中分配的内存。我需要时可以用东西清理内存吗？

#include<stdio.h>
#include<stdlib.h>
#define MAXROW 3
#define MAXCOL 4

int main()
{
    int **p, i, j;
    p = (int **) malloc(MAXROW * sizeof(int*));
    return 0;
}

2 个解决方案

#1

It's simple. You can use this code to clean your only used variable.

这很简单。您可以使用此代码清除您唯一使用的变量。

#include<stdio.h>
#include<stdlib.h>
#define MAXROW 3
#define MAXCOL 4

int main()
{
     int **p, i, j;
     p = (int **) malloc(MAXROW * sizeof(int*)); 
     free(p);
     return 0;
}

#2

Point 1

第1点

You cannot free some memory. You have to free all. To elaborate, whatever memory has been allocated by a single call to malloc() or family, will be free-d at a time. You cannot free half (or so) of the allocated memory.

你不能释放一些记忆。你必须释放所有。详细说明，通过单次调用malloc（）或family分配的内存，一次只能*调用。你不能释放一半（或左右）分配的内存。

Point 2

第2点

Please do not cast the return value of malloc() and family in C.
请不要在C中强制转换malloc（）和family的返回值。
You should always write sizeof(*ptr) instead of sizeof(type*).
你应该总是写sizeof（* ptr）而不是sizeof（type *）。

Point 3

第3点

You can use the free() to free the allocated memory.

您可以使用free（）释放分配的内存。

for example, see the below code and please notice the inline comments.

例如，请参阅以下代码，请注意内联注释。

#include<stdio.h>
#include<stdlib.h>
#define MAXROW 3
#define MAXCOL 4

int main(void)                        //notice the signature of main
{
    int **p = NULL;                      //always initialize local variables
    int i = 0, j = 0;

    p = malloc(MAXROW * sizeof(*p));  // do not cast and use sizeof(*p)
    if (p)                            //continue only if malloc is a success
    {

        //do something
        //do something more

        free(p);                      //-----------> freeing the memory here.
    }
    return 0;
}

#1