Task: Rosetta Code_Rank languages by popularity
C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>

const char * lang_url = "http:
		"list=categorymembers&cmtitle=Category:Programming_Languages&"
		"cmlimit=500&format=json";
const char * cat_url = "http:

#define BLOCK 1024
char *get_page(const char *url)
{
	char cmd[1024];
	char *ptr, *buf;
	int bytes_read = 1, len = 0;
	sprintf(cmd, "wget -q \"%s\" -O -", url);
	FILE *fp = popen(cmd, "r");
	if (!fp) return 0;
	for (ptr = buf = 0; bytes_read > 0; ) {
		buf = realloc(buf, 1 + (len += BLOCK));
		if (!ptr) ptr = buf;
		bytes_read = fread(ptr, 1, BLOCK, fp);
		if (bytes_read <= 0) break;
		ptr += bytes_read;
	}
	*++ptr = '\0';
	return buf;
}

char ** get_langs(char *buf, int *l)
{
	char **arr = 0;
	for (*l = 0; (buf = strstr(buf, "Category:")) && (buf += 9); ++*l)
		for (	(*l)[arr = realloc(arr, sizeof(char*)*(1 + *l))] = buf;
			*buf != '"' || (*buf++ = 0);
			buf++);

	return arr;
}

typedef struct { const char *name; int count; } cnt_t;
cnt_t * get_cats(char *buf, char ** langs, int len, int *ret_len)
{
	char str[1024], *found;
	cnt_t *list = 0;
	int i, llen = 0;
	for (i = 0; i < len; i++) {
		sprintf(str, "/wiki/Category:%s", langs[i]);
		if (!(found = strstr(buf, str))) continue;
		buf = found + strlen(str);

		if (!(found = strstr(buf, "</a> ("))) continue;
		list = realloc(list, sizeof(cnt_t) * ++llen);
		list[llen - 1].name = langs[i];
		list[llen - 1].count = strtol(found + 6, 0, 10);
	}
	*ret_len = llen;
	return list;
}

int _scmp(const void *a, const void *b)
{
	int x = ((const cnt_t*)a)->count, y = ((const cnt_t*)b)->count;
	return x < y ? -1 : x > y;
}

int main()
{
	int len, clen;
	char ** langs = get_langs(get_page(lang_url), &len);
	cnt_t *cats = get_cats(get_page(cat_url), langs, len, &clen);
	qsort(cats, clen, sizeof(cnt_t), _scmp);
	while (--clen >= 0)
		printf("%4d %s\n", cats[clen].count, cats[clen].name);

	return 0;
}

Go: package main

import (
	"encoding/xml"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"regexp"
	"sort"
	"strconv"
	"strings"
)

var baseQuery = "http:
	"&format=xml&list=categorymembers&cmlimit=500"

func req(u string, foundCm func(string)) string {
	resp, err := http.Get(u)
	if err != nil {
		log.Fatal(err) 
	}
	defer resp.Body.Close()
	for p := xml.NewDecoder(resp.Body); ; {
		t, err := p.RawToken()
		switch s, ok := t.(xml.StartElement); {
		case err == io.EOF:
			return ""
		case err != nil:
			log.Fatal(err)
		case !ok:
			continue
		case s.Name.Local == "cm":
			for _, a := range s.Attr {
				if a.Name.Local == "title" {
					foundCm(a.Value)
				}
			}
		case s.Name.Local == "categorymembers" && len(s.Attr) > 0 &&
			s.Attr[0].Name.Local == "cmcontinue":
			return url.QueryEscape(s.Attr[0].Value)
		}
	}
	return ""
}


type pop struct {
	string
	int
}
type popList []pop

func (pl popList) Len() int      { return len(pl) }
func (pl popList) Swap(i, j int) { pl[i], pl[j] = pl[j], pl[i] }
func (pl popList) Less(i, j int) bool {
	switch d := pl[i].int - pl[j].int; {
	case d > 0:
		return true
	case d < 0:
		return false
	}
	return pl[i].string < pl[j].string
}

func main() {
	
	langMap := make(map[string]bool)
	storeLang := func(cm string) {
		if strings.HasPrefix(cm, "Category:") {
			cm = cm[9:]
		}
		langMap[cm] = true
	}
	languageQuery := baseQuery + "&cmtitle=Category:Programming_Languages"
	continueAt := req(languageQuery, storeLang)
	for continueAt != "" {
		continueAt = req(languageQuery+"&cmcontinue="+continueAt, storeLang)
	}
	
	s := make(popList, 0, len(langMap))

	
	resp, err := http.Get("http:
		"?title=Special:Categories&limit=5000")
	if err != nil {
		log.Fatal(err)
	}
	page, err := ioutil.ReadAll(resp.Body)
	resp.Body.Close()

	
	rx := regexp.MustCompile("<li><a.*>(.*)</a>.*[(]([0-9]+) member")
	for _, sm := range rx.FindAllSubmatch(page, -1) {
		ls := string(sm[1])
		if langMap[ls] {
			if n, err := strconv.Atoi(string(sm[2])); err == nil {
				s = append(s, pop{ls, n})
			}
		}
	}

	
	sort.Sort(s)
	lastCnt, lastIdx := -1, 1
	for i, lang := range s {
		if lang.int != lastCnt {
			lastCnt = lang.int
			lastIdx = i + 1
		}
		fmt.Printf("%3d. %3d - %s\n", lastIdx, lang.int, lang.string)
	}
}