// URL_test.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

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


// 判断字符是否需要进行 URL 编码
static bool needs_encoding(char c)
{
  if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') ||
      (c >= '0' && c <= '9') || c == '_' || c == '.' || c == ':' || c == '-' || c == '/' || c == '?' || c == '&' || c == '=')
  {
    return false;
  }
  return true;
}

// 对字符进行 URL 编码，返回编码后的字符串
static char *url_encode_char(char c)
{
  static char hex[] = "0123456789ABCDEF";
  char *encoded = (char *)malloc(4);
  if (encoded)
  {
    encoded[0] = '%';
    encoded[1] = hex[(c >> 4) & 0x0F];
    encoded[2] = hex[c & 0x0F];
    encoded[3] = '\0';
  }
  return encoded;
}

// 对字符串进行 URL 编码，返回编码后的字符串
char *encode_uri(const char *str)
{
  int len = strlen(str);
  char *encoded = (char *)malloc(3 * len + 1);
  if (encoded)
  {
    int pos = 0;
    for (int i = 0; i < len; i++)
    {
      if (needs_encoding(str[i]))
      {
        char *encoded_char = url_encode_char(str[i]);
        if (encoded_char)
        {
          strcpy(&encoded[pos], encoded_char);
          pos += 3;
          free(encoded_char);
        }
      }
      else
      {
        encoded[pos++] = str[i];
      }
    }
    encoded[pos] = '\0';
  }
  return encoded;
}

int main()
{

  const char *uri = "http://www.test.url编码处理测试.png";
  char *encoded_uri = encode_uri(uri);
  if (encoded_uri)
  {
    printf("原始 URI: %s\n", uri);
    printf("编码后 URI: %s\n", encoded_uri);
    free(encoded_uri);
  }
  else
  {
    printf("URI 编码失败\n");
  }
  return 0;
}

运行效果