二维指针动态分配内存连续问题深入分析二维指针动态分配内存连续问题深入分析
首先,小编先贴出测试代码:
代码如下:
#include <cstdlib>
#include <iostream>
using namespace std;
#define nWidth 3
#define nHeight 4
//内存是否连续分配问题
int main(int argc, char *argv[])
{
int **p = NULL;
p = (int**)malloc(nWidth*sizeof(int*));
if(p == NULL)
return -1;
cout<<“内存的不连续分配:”<<endl;
for(int j = 0; j< nWidth; j++)
{
p[j] = (int*)malloc(nHeight*sizeof(int));
if(p[j] == NULL)
return -1;
}
for(int i = 0; i < nWidth; i++)
for(int j = 0; j < nHeight; j++)
{
printf(“%p “,&p[i][j]);
if(j == nHeight-1)
cout<<endl;
}
cout<<endl;
for(int j = 0; j < nWidth; j++)
{
free(p[j]);
p[j] = NULL;
}
free(p);
p = NULL;
int **q = NULL;
q = (int**)malloc(nWidth*sizeof(int*));
if(q == NULL)
return -1;
cout<<“内存的连续分配:”<<endl;
q[0] = (int*)malloc(nWidth*nHeight*sizeof(int));
if(q[0] == NULL)
{
free(q);
return -1;
}
for(int i = 1;i < nWidth; i++)
q[i] = q[i-1] + nHeight;
for(int i = 0; i < nWidth; i++)
for(int j = 0; j < nHeight; j++)
{
printf(“%p “,&q[i][j]);
if(j == nHeight-1)
cout<<endl;
}
cout<<endl;
free(q[0]);
q[0] = NULL;
free(q);
q = NULL;
system(“PAUSE”);
return EXIT_SUCCESS;
}