uniqurl.c

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

typedef struct param {
    const char *text;
    int len;
} param;

param params[256];

int param_compare(const void* a, const void* b)
{
    param *s1 = (param *)a;
    param *s2 = (param *)b;
    int n = s1->len > s2->len ? s2->len : s1->len;
    return strncmp(s1->text, s2->text, n);

}

char *url_sort(const char *in)
{
    const char *pc = in;
    char c = *in;
    const char *real_in = NULL;
    int keys_count = 0;
    char *out = (char *)malloc(1024);
    if (!out)
        return NULL;

    while (c != '\n' && c != '\0') {
        pc++;
        if (c == '?') {
            real_in = pc;
            c = *pc;
            break;
        }
        c = *pc;
    }
    if (!real_in)
        return strcpy(out, in);
    if (pc == in)
        return NULL;

    do {
        params[keys_count].text = pc;
        c = *pc;
        while (c != '\n' && c != '\0' && c != '&')
            c = *(++pc);
        if (c == '&') {
            pc++;
            params[keys_count].len = pc - params[keys_count].text - 1;
            params[++keys_count].text = pc;
            continue;
        }
        params[keys_count].len = pc - params[keys_count].text;
        keys_count++;
        break;
    } while (1);

    int i;
    char *o = out;
    /*
    for (i = 0; i < keys_count; i++) {
        printf("%s", params[i].text);
        printf("%d\n", params[i].len);
    }
    */

    qsort(params, keys_count, sizeof(param), param_compare);

    memcpy(o, in, real_in - in + 1);
    o += real_in - in;
    for (i = 0; i < keys_count; i++) {
        //printf("%s", params[i].text);
        //printf("%d\n", params[i].len);
        memcpy(o, params[i].text, params[i].len);
        o += params[i].len;
        *o++ = '&';
    }
    *(o - 1) = '\0';
    return out;
}

int main(int argc, char** argv){
	char buf[2048];
	char* out;
	while(fgets(buf,2048,stdin) != NULL){
		//chopping off newlines
		buf[strcspn(buf, "\n")] = '\0';
		if (buf[0] == '\0')
		    continue;
		out = url_sort(buf);
		printf("%s\n", out);
		free(out);
		// printf("Orig: %s\nSort: %s\n\n",buf, out );
	}
	return 0;
}