c语言实现urlencode

#include <stdio.h> 
#include <string.h> 
 
/**
* @brief URLEncode 对字符串URL编码
*
* @param str 原字符串
* @param strSize 原字符串长度(不包括最后的\0)
* @param result 结果缓冲区的地址
* @param resultSize 结果缓冲区的大小(包括最后的\0)
*
* @return: >0:resultstring 里实际有效的长度
*            0: 解码失败.
*/ 
int URLEncode(const char* str, const int strSize, char* result, const int resultSize) 
{ 
    int i; 
    int j = 0;//for result index 
    char ch; 
 
    if ((str==NULL) || (result==NULL) || (strSize<=0) || (resultSize<=0)) { 
        return 0; 
    } 
 
    for ( i=0; (i<strSize)&&(j<resultSize); ++i) { 
        ch = str[i]; 
        if (((ch>='A') && (ch<'Z')) || 
            ((ch>='a') && (ch<'z')) || 
            ((ch>='0') && (ch<'9'))) { 
            result[j++] = ch; 
        } else if (ch == ' ') { 
            result[j++] = '+'; 
        } else if (ch == '.' || ch == '-' || ch == '_' || ch == '*') { 
            result[j++] = ch; 
        } else { 
            if (j+3 < resultSize) { 
                sprintf(result+j, "%%%02X", (unsigned char)ch); 
                j += 3; 
            } else { 
                return 0; 
            } 
        } 
    } 
 
    result[j] = '\0'; 
    return j; 
} 
 
int main(int argc, char* argv[]) 
{ 
    char* src = argv[1]; 
    unsigned int srclength = strlen(src); 
    printf("src length: %d\n", strlen(src)); 
     
 
    char obj[100] = {0}; 
    URLEncode(src, srclength, obj, 100); 
 
    printf("obj: %s\n", obj); 
    printf("obj: %d\n", strlen(obj)); 
 
    return 0; 
}