OJ Board

how do u sort character arrays in C

Normally I use Bubbel Sort charecter arrays. But its not fast enough.
And for string I use built in Qsort.

I use selection sort for short strings (because it's easy to remember and implement) and counting sort for long strings (because it's fast).

I use the built-in quick sort as I think it saves considerable coding time.

[c]int cmp( char *a, char *b ) {
if ( *a > *b ) return 1;
if ( *a < *b ) return -1;
return 0;
}

int main() {
char a[] = "Hey hey, I am Larry!";
qsort( a, strlen( a ), sizeof( char ), cmp );
}
[/c]

Hope it helps.. =)

Note that, most/some people write the compare like this:
[c]int cmp( int *a, int *b ) {
return *a - *b;
}[/c]

(as I used to, actually) but is prone to over/underflows.. so be careful.. =)

Well to be accurate the sort function should be written as:
[c]
#include <stdlib.h>
struct m
{
int x, y;
};

int cmp( const void *l, const void *r )
{
struct m *a = (struct m *)l;
struct m *b = (struct m *)r;

if ( a->x > b-x )
return 1;
if ( b->x > a->x )
return -1;
return 0;
}

int main( void )
{
struct m A[10];
qsort(A, 10, sizeof(m), cmp);
return 0;
}
[/c]

Otherwise the compiler will complain, and your sort function might not work as expected.

Regards,
Suman.

It compiles fine with -ANSI flag without warning, but if you understand it, it's fine.. =)

If you really want to be anal, you shouldn't use greater than and less than on the struct directly like you did anyhow.. it's might not work for everything.. =P[/c]

You are right Larry, I was in a hurry and it was a typo.I didnt mean to compare structs !!!!

Thanks!