c语言unsigned char转成字符串

    unsigned char MD[16];
    MD5((unsigned char*)p,statbuf.st_size,MD);//获得MD5值 适用于mmap传输
    char buffer[1000]={0};
    for(int i = 0; i < 16; i++)  {  
        //格式化输str,每unsigned char 转换字符占两位置%x写输%X写输  
        sprintf(buffer + i*2, "%02x", MD[i]);  
    }