什么是C ++中的自由函数？
C/C++库函数voidfree（void*ptr）取消分配先前由对calloc，malloc或realloc的调用分配的内存。以下是free()函数的声明。
void free(void *ptr)
该函数需要一个指针ptr。这是指向以前分配有malloc，calloc或realloc的内存块的指针。如果将空指针作为参数传递，则不会发生任何操作。
示例
#include <iostream>
#include <cstdlib>
#include <cstring>
using namespace std;
int main () {
char *str;
/* Initial memory allocation */
str = (char *) malloc(15);
strcpy(str, "nhooo");
cout << "String = "<< str <<", Address = "<< &str << endl;
/* Reallocating memory */
str = (char *) realloc(str, 25);
strcat(str, ".com");
cout << "String = "<< str <<", Address = "<< &str << endl;
/* Deallocate allocated memory */
free(str);
return(0);
}输出结果
String = nhooo, Address = 0x22fe38 String = nhooo.com, Address = 0x22fe38