二级指针三种内存模型综合训练

Posted 2020-11-30 wanghao-boke

 

/***
point_practice.c
***/
#include<stdio.h>
#include<string.h>
#include<stdlib.h> 

int sort( char **myp1 /*in*/, int num1, char (*myp2)[30], int num2, char ***myp3, int *num3)
{
    int i = 0, j = 0, k = 0;
    int tmplen;
    char **p3 = NULL;
    char *tmpP = NULL;
    p3 = (char **)malloc((num1 + num2) * sizeof(char *));
    if (NULL == p3)
    {
        return -1;
    }
    
    for (i = 0; i < num1; i++)
    {
        tmplen = strlen(myp1[i]) + 1;
        p3[i] = (char *)malloc(tmplen * sizeof(char));
        
        if(NULL == p3[i])
        {
            return -2;
        }
        strcpy(p3[i],myp1[i]);
    }
    
    for (j = 0; j < num2; j++,i++)
    {
        tmplen = strlen(myp2[j]) + 1;
        p3[i] = (char *)malloc(tmplen * sizeof(char));
        
        if (NULL == p3[i])
        {
            return -3;
        }
        strcpy(p3[i], myp2[j]);
    }
    
    tmplen = num1 + num2;
    
    for (i = 0; i < tmplen; i++)
    {
        for (j = i + 1; j < tmplen; j++)
        {
            if (strcmp(p3[i], p3[j]) > 0)
            {
                tmpP = p3[i];
                p3[i] = p3[j];
                p3[j] = tmpP;
            }
        } 
    }
    *num3 = tmplen;
    *myp3 = p3;     
    return 0;
}

void sortFree(char **p, int len)
{
    int i;
    if (NULL == p)
    {
        return ;
    }
    
    for (i = 0;  i < len; i++)
    {
        free(p[i]);
    }
    free(p);
}

/*
把二级指针指向二维内存释放掉
同时间接修改实参的地址   
*/ 
void sortFree01(char ***myp, int len)  
{
    int i = 0;
    char **p = NULL;
    if (myp == NULL)
    {
        return ;
    }
    
    p = *myp;
    if (p == NULL)
    {
        return;
    }
    
    for (i = 0; i < len; i++)
    {
        free(p[i]);
    }
    free(p);
    *myp = NULL; //间接赋值是指针最大的意义 
    
}

int main()
{
    int ret;
    int i;
    
    char *p1[] = {"aaaaaa","cccccc","bbbbbb"};
    char buf2[10][30] = {"11111","3333333","222222"};
    char **p3 = NULL;
    int len1,len2,len3;
    
    len1 = sizeof(p1)/sizeof(*p1);
    len2 = 3;
    
    ret = sort(p1, len1, buf2, len2, &p3, &len3);
    if (0 != ret)
    {
        printf("func sort() err:%d
",ret);
        return ret;
    }
    
    for (i = 0; i < len3 ;i++)
    {
         printf("%s
",p3[i]);
    }
    
    return 0;
}