指针的指针，以及指针传递

 

#include <cstddef>
#include <cstdlib>
#include <iostream>
#include "string.h"
using namespace std;


void GetMemory(char **p,int num)
{
    *p = (char *)malloc(sizeof(char)*num);
    cout << "&p = " << p << endl;

}
char *GetMemory(char *p,int num)
{
    p = (char *)malloc(sizeof(char)*num);
    return p;
}
int main()
{
    char *a = NULL;
    GetMemory(&a, 10);//传了一个指向指针的指针，
    strcpy(a,"helloworld");
    cout << "&a = " << &a << endl;
    cout << "a = " << a << endl;
    cout << "*a = "<< *a <<endl;

    char *b = NULL;
    b = GetMemory(b,100);
    strcpy(b, "hello");
    cout << "b = " << b << endl;

    return 0;
}