edaBit-coding-challenges/Is-It-a-Valid-RGBA-Color/code.cpp

std::string okay(std::string s) {
    std::string temp;
    for(int i = 0; i<s.size(); i++) {
        if(std::isdigit(s[i])) temp.push_back(s[i]);
    }
    return temp;
}

std::string fokay(std::string s) {
    std::string temp;
    for(int i = 0; i<s.size(); i++) {
        // floating pt can have a decimal
        if(std::isdigit(s[i]) || ('.' == s[i])) temp.push_back(s[i]);
        // again, if the first character is +/- this is ok
        if(0 == temp.size() && (('-' == s[i]) || ('+' == s[i]))) temp.push_back(s[i]);
    }
    return temp;
}

/*  Given an RGB(A) CSS color, determine whether its
 *  format is valid or not. Create a function that takes a string
 *  (e.g. "rgb(0, 0, 0)") and return true if it's format is correct,
 *  otherwise return false.
 *  Alpha is between 0 and 1.
 *  There are a few edge cases. Check out the Tests tab to know more.
 */
bool validColor(std::string color) {
	
	  // [!] I DO NOT AGREE WITH THIS TEST (whitespace_before_parenthesis)
	  if(std::string::npos != color.find("rgb ")) return false;
	  // [!] THIS TEST IS HIGHLY QUESTIONABLE (rgb_with_4_numbers / rgba_with_3_numbers)
	  int expected = std::string::npos != color.find("rgba") ?4 :3;
	  // [!] DEFINITELY NOT OK (numbers_below_0)
	  if(std::string::npos != color.find('-')) return false;
	  // [?] IDK, THIS IS MAYBE OKAY (numbers_above_100_percent)
	  bool checkPercent = std::string::npos != color.find('%');
	
    //  find the first comma, store the preceding number
    std::vector <std::string> rgb;
    for(int i = 0; i<3; i++){
        int position = color.find(',');
        //  if a comma isn't found, stop.
        if(std::string::npos == position)break;
        //  empty string is invalid parameter
        if(!position) return false;
        //  a comma was found, copy everything before comma.
        rgb.push_back(okay(color.substr(0,position)));
        //  delete the commma and everything before it.
        color = color.substr(position+1,std::string::npos);
    }

    //  this is the third/fourth number
    if(color.size()){rgb.push_back(fokay(color));}
    if(rgb.size() != expected) return false;
    for(int j = 0;j<rgb.size();j++){
        if(j == 3){
            float rgbA = std::stof(rgb[3]);
            if(0>rgbA || rgbA>1){return false;}
        } else {
            int aNumber = std::stoi(rgb[j], nullptr, 10);
            //  if aNumber is greater than 255 or less than 0, then its not valid
            if(0>aNumber || aNumber>255) return false;
						// [?] see (numbers_above_100_percent)
					  if(checkPercent && aNumber>100) return false;
        }
    }
    return true;
}