问题描述

C语言：用qsort()和strcmp实现对字符串数组的字典序排序

#include
#include
#include
int mycomp(const void p1,const void *p2)
{
const char *a1=(const char)p1;
const char a2=(const char)p2;
return strcmp(a1,a2);
}
int main()
{
int i;
char a[5]={"ssioo","abcde","bcade","bacd","jjjjj"};
qsort(a,5,sizeof(char),mycomp);
for(i=0;i<5;i++)
{
printf("%s ",a[i]);
}

return 0;

}
warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]|
输出结果是没有经过排序的
问：要如何修改？要实现字符串数组字典序排序有什么思路？

解决方案

 #include<stdio.h>
#include<stdlib.h>
#include<string.h>

int mycomp(const void* a,const void* b)
{
    return strcmp(*(char **)a,*(char**)b);
}

int main()
{
    char a[5][20] = {"ssioo","abcde","bcade","bacd","jjjjj"};
    char** s = (char **)new char[20];
    for(int i = 0; i < 5; i++)
    {
        s[i] = new char[20];
        strcpy(s[i], a[i]);
    }
    qsort(s, 5, sizeof(char *), mycomp);
    for(int i = 0; i < 5; i++)
        printf("%sn", s[i]);
    return 0;
}

输出
abcde
bacd
bcade
jjjjj
ssioo

解决方案二：

 #include<stdio.h>
#include<stdlib.h>
#include<string.h>

int mycomp(const void* a,const void* b)
{
    return strcmp(*(char **)a,*(char**)b);
}

int main()
{
    char *a[] = {"ssioo","abcde","bcade","bacd","jjjjj"};
    qsort(a, 5, sizeof(char *), mycomp);
    for(int i = 0; i < 5; i++)
        printf("%sn", a[i]);
    return 0;
}

解决方案三：

const char *a1=(const char)p1;
const char a2=(const char)p2;//这些都是类型不匹配