URL encode C 实现

  今天要做点东西， 需要用到URL编码， 找到的几个例子在解析中文的时候遇到点困难，一下是在 sina api c++ sdk 中挑选出来的  做了一下 测试 希望对后来人有所帮助：

 

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

static void *xmalloc_fatal(size_t size) {
  if (size==0) return NULL;
  fprintf(stderr, "Out of memory.");
  exit(1);
  return 0;
}

void *xmalloc (size_t size) {
  void *ptr = malloc (size);
  if (ptr == NULL) return xmalloc_fatal(size);
  return ptr;
}

void *xcalloc (size_t nmemb, size_t size) {
  void *ptr = calloc (nmemb, size);
  if (ptr == NULL) return xmalloc_fatal(nmemb*size);
  return ptr;
}

void *xrealloc (void *ptr, size_t size) {
  void *p = realloc (ptr, size);
  if (p == NULL) return xmalloc_fatal(size);
  return p;
}

char *xstrdup (const char *s) {
  void *ptr = xmalloc(strlen(s)+1);
  strcpy (ptr, s);
  return (char*) ptr;
}
/**
 * Escape 'string' according to RFC3986 and
 * http://oauth.net/core/1.0/#encoding_parameters.
 *
 * @param string The data to be encoded
 * @return encoded string otherwise NULL
 * The caller must free the returned string.
 */
char *oauth_url_escape(const char *string) {
  size_t alloc, newlen;
  char *ns = NULL, *testing_ptr = NULL;
  unsigned char in;
  size_t strindex=0;
  size_t length;

  if (!string) return xstrdup("");

  alloc = strlen(string)+1;
  newlen = alloc;

  ns = (char*) xmalloc(alloc);

  length = alloc-1;
  while(length--) {
    in = *string;

    switch(in){
    case '0': case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9':
    case 'a': case 'b': case 'c': case 'd': case 'e':
    case 'f': case 'g': case 'h': case 'i': case 'j':
    case 'k': case 'l': case 'm': case 'n': case 'o':
    case 'p': case 'q': case 'r': case 's': case 't':
    case 'u': case 'v': case 'w': case 'x': case 'y': case 'z':
    case 'A': case 'B': case 'C': case 'D': case 'E':
    case 'F': case 'G': case 'H': case 'I': case 'J':
    case 'K': case 'L': case 'M': case 'N': case 'O':
    case 'P': case 'Q': case 'R': case 'S': case 'T':
    case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
    case '_': case '~': case '.': case '-':
      ns[strindex++]=in;
      break;
    default:
      newlen += 2; /* this'll become a %XX */
      if(newlen > alloc) {
        alloc *= 2;
        testing_ptr = (char*) xrealloc(ns, alloc);
        ns = testing_ptr;
      }
      snprintf(&ns[strindex], 4, "%%%02X", in);
      strindex+=3;
      break;
    }
    string++;
  }
  ns[strindex]=0;
  return ns;
}

int main(int argc, char *argv[])
{
  char src[1024];
   char* sb;
  strcpy(src,"http://www.google.com/?=春节1234");
  sb= malloc(5*strlen(src));
  sb = oauth_url_escape(src);

        printf("url %s/n src:%d-dest:%d/n",src,strlen(src),strlen(sb));
        printf("encoded url %s",sb);

  system("PAUSE"); 
  free(sb);
  return 0;
}