day4_二级指针做输入输出的三种内存模型

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一、第一种内存模型

#define  _CRT_SECURE_NO_WARNINGS#include <stdio.h>#include <stdlib.h>#include <string.h>#include <windows.h>//二级指针做输入的第一种内存模型int main41(){    int i = 0;    int j = 0;    int num = 0;    char *tmp = NULL;    //数组的每一个元素是指针  myArray是指针数组    char *myArray[] = {"aaaa","bbbb","cccc","1111"};    num = sizeof(myArray)/sizeof(myArray[0]);    printf("排序之前：\n");    for(i = 0; i<num; i++)    {//        printf("%s \n",myArray[i]);        printf("%s \n",*(myArray + i));    }    //排序    //改变的是指针的指向 没有改变指针所指向的内存空间    for(i = 0; i<num; i++)    {        for(j = 0; j<num; j++)        {            if(strcmp(myArray[i],myArray[j]) > 0)            {                tmp = myArray[i]; //交换的是数组元素 即指针的值                myArray[i] = myArray[j];                myArray[j] = tmp;            }        }    }    printf("排序之后：\n");    for(i = 0; i<num; i++)    {        printf("%s \n",*(myArray + i));    }    system("pause");    return 0;}//函数封装void printmyArray11(char **myArray,int num){    int i = 0;     for(i = 0; i<num; i++)    {        //printf("%s \n",myArray[i]);        printf("%s \n",*(myArray + i));    }}//排序    //改变的是指针的指向 没有改变指针所指向的内存空间void sortmyArray(char **myArray,int num){    int i = 0;    int j = 0;    char *tmp = NULL;    for(i = 0; i<num; i++)    {        for(j = 0; j<num; j++)        {            if(strcmp(myArray[i],myArray[j]) > 0)            {                tmp = myArray[i]; //交换的是数组元素 即指针的值                myArray[i] = myArray[j];                myArray[j] = tmp;            }        }    }}int main(){    int num = 0;    //数组的每一个元素是指针  指针数组    char *myArray[] = {"aaaa","bbbb","cccc","1111"};    num = sizeof(myArray)/sizeof(myArray[0]);    printf("排序之前：\n");    printmyArray11(myArray,num);    //排序    sortmyArray(myArray,num);    printf("排序之后：\n");    printmyArray11(myArray,num);    system("pause");    return 0;}

二、第二种内存模型

#define  _CRT_SECURE_NO_WARNINGS#include <stdio.h>#include <stdlib.h>#include <string.h>#include <windows.h>//二级指针做输入的第2种内存模型//打印 排序//封装成函数int main51(){    int i = 0;    int j = 0;    int num = 4;    char mybuf[30];    char tmpbuf[30];    char myArray[10][30] = {"aaaa","bbbb","cccc","2222"};    //编译器只关心有10行30列    myarray+1跳30个字节  多维数组名的本质    //打印    printf("排序之前：\n");    for(i = 0; i<num; i++)    {        printf("%s \n",myArray[i]);    }    //排序    for(i = 0; i<num; i++)    {        for(j = i+1; j<num; j++)        {            if(strcmp(myArray[i],myArray[j]) > 0)            {                strcpy(tmpbuf,myArray[i]);//交换的是内存块                strcpy(myArray[i],myArray[j]);                strcpy(myArray[j],tmpbuf);            }        }    }    printf("排序之后：\n");    for(i = 0; i<num; i++)    {        printf("%s \n",myArray[i]);    }    system("pause");    return 0;}//函数封装//打印void printmyArray51_error(char **myArray,int num){    int i = 0;     for(i = 0; i<num; i++)    {        //问题的本质是：第二种myArray + i和第一种myArray + i不一样        //指针的步长不一样 即指针所指向的内存空间数据类型不一样        printf("%s \n",*(myArray + i));    }}void printmyArray51(char myArray[10][30],int num){    int i = 0;     for(i = 0; i<num; i++)    {        printf("%s \n",*(myArray + i));    }}//交换的是内存块void sortmyArray02(char myArray[10][30],int num){    int i = 0;    int j = 0;    char tmpbuf[30];    for(i = 0; i<num; i++)    {        for(j = i+1; j<num; j++)        {            if(strcmp(myArray[i],myArray[j]) > 0)            {                strcpy(tmpbuf,myArray[i]);//交换的是内存块                strcpy(myArray[i],myArray[j]);                strcpy(myArray[j],tmpbuf);            }        }    }}int main(){    int num = 4;    char myArray[10][30] = {"aaaa","bbbb","cccc","2222"};    printf("排序之前：\n");    printmyArray51(myArray,num);    //排序    sortmyArray02(myArray,num);    printf("排序之后：\n");    printmyArray51(myArray,num);    system("pause");    return 0;}

三、第三种内存模型

#define  _CRT_SECURE_NO_WARNINGS#include <stdio.h>#include <stdlib.h>#include <string.h>#include <windows.h>//二级指针做输入的第3种内存模型//int main61(){    char **p2 = NULL;    int i = 0;    int j = 0;    int num = 5;    char *tmp = NULL;    p2 = (char **)malloc(sizeof(char *)*num);    for(i = 0; i<num; i++)    {        p2[i] = (char *)malloc(sizeof(char)*100);        sprintf(p2[i],"%d%d%d",i+1,i+1,i+1);    }    printf("排序之前：\n");    for(i = 0; i<num; i++)    {        printf("%s \n",p2[i]);    }    //排序 交换的是指针    for(i = 0; i<num; i++)    {        for(j = i+1; j<num; j++)        {            if(strcmp(p2[i],p2[j]) < 0)            {                tmp = p2[i];                p2[i] = p2[j];                p2[j] = tmp;            }        }    }    printf("排序之后：\n");    for(i = 0; i<num; i++)    {        printf("%s \n",p2[i]);    }    //释放内存    for(i = 0; i<num; i++)    {        if(p2 != NULL)        {            free(p2[i]);            p2[i] = NULL;        }    }    if(p2[i] != NULL)    {        free(p2[i]);    }    system("pause");    return 0;}//函数封装//分配内存char **getMen61(int num){    char **p2 = NULL;    int i = 0;    p2 = (char **)malloc(sizeof(char *)*num);    if(p2 == NULL)    {        return;    }    for(i = 0; i<num; i++)    {        p2[i] = (char *)malloc(sizeof(char)*100);        sprintf(p2[i],"%d%d%d",i+1,i+1,i+1);    }    return p2;}//打印void printmyArray61(char **myArray,int num){    int i = 0;     for(i = 0; i<num; i++)    {        printf("%s \n",*(myArray + i));    }}//排序void sortmyArray61(char **myArray,int num){    int i = 0;    int j = 0;    char *tmp = NULL;    for(i = 0; i<num; i++)    {        for(j = 0; j<num; j++)        {            if(strcmp(myArray[i],myArray[j]) > 0)            {                tmp = myArray[i]; //交换的是数组元素 即指针的值                myArray[i] = myArray[j];                myArray[j] = tmp;            }        }    }}//释放内存void getMen61_free(char **p2,int num){    int i = 0;    for(i = 0; i<num; i++)    {        if(p2 != NULL)        {            free(p2[i]);            p2[i] = NULL;        }    }    if(p2[i] != NULL)    {
        free(p2[i]);    }}int main(){    char **p2 = NULL;    int num = 5;    char tmpbuf[100];    //分配内存    p2 = getMen61(num);    printf("排序之前：\n");    printmyArray61(p2,num);    //排序 交换的是内存    sortmyArray61(p2,num);    printf("排序之后：\n");    printmyArray61(p2,num);    //释放内存    getMen61_free(p2,num);//p2是一个野指针    system("pause");    return 0;}

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