使用qsort对字符串排序

问题描述

我正在尝试使用stdlib qsort对字符串数组进行排序。有人可以指出我缺少的步骤。

I am trying to sort an array of strings using stdlib qsort. Could anyone point to me the step I am missing.

int compare(const void* a, const void* b)
{
    const char *ia = (const char *)a;
    const char *ib = (const char *)b;
    return strcmp(ia, ib);
}

//utility to print strings
void print_strs(char name[][10],int len){

    int i=0;
    len = 5;
    for(i=0;i<len;i++){
        printf("%s \n",name[i]);
    }
}

int _tmain(int argc, _TCHAR* argv[])
{
    char names[5][10] = {"norma","daniel","carla","bob","adelle"};
    int size1 = sizeof(names[0]);
    int s2 = sizeof(names)/size1;
    print_strs(names,5);
    qsort(names,s2,sizeof(char),compare);
    printf("\n==================\n");
    print_strs(names,5);
    return 0;
}

以下是输出中的问题：

1。未排序的字符串
2.数组的第一个字符串不正确（Norma打印为amnor）。

1.unsorted strings 2.first string of the array is incorrect(Norma printed as amnor).

norma
daniel
carla
bob
adelle
==================
amnor
daniel
carla
bob
adelle

推荐答案

您在调用 qsort 时传递了错误的 size 。您正在传递 sizeof（char）作为单个元素的大小，这是错误的。在您的情况下，每个元素都是一个包含十个字符的字符串。

You are passing wrong size while calling qsort. You are passing sizeof(char) as the size of your individual element, which is wrong. In your case each individual element is a string with ten characters.

因此，您可以通过调用 qsort as：

So, you can correct that by either calling qsort as:

qsort(names,s2,sizeof(char) * 10,compare);

或者，因为您已经在 size1 ，您可以这样使用：

Or, as you already have captured this value in size1, you can use that, as:

qsort(names,s2,size1,compare);

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