sorting of strings using qsort

Question

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;
}

Following are the issues in the output :

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

Make up your mind about whether you're trying to sort an array of char *s (as your comparison function is defined) or an array of char[10]s (as the array is declared) or an array of chars (according to the size you passed to qsort). — Stack Exchange Broke The Law
– Stack Exchange Broke The Law, Commented Aug 1, 2016 at 1:51

sps · Accepted Answer · 2016-08-01 02:10:34Z

1

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.

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

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

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

qsort(names,s2,size1,compare);

answered Aug 1, 2016 at 2:10

sps

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