UTF-8字符过滤

 

编码的过程中，只针对UTF-8字符(!至~)进行处理，所以需要实现字符过滤功能筛选出非特殊字符。

//只对非UTF-8字符进行编码
static const char *hex = "0123456789abcdef";
if(c > '!' && c <= '~') {                    
    ret.push_back(c);
} else { 
    ret.append("\\x");
    unsigned char d = c;
    ret.push_back(hex[d >> 4]);
    ret.push_back(hex[d & 0x0f]);
}