Given a string str, the task is to check whether the given string is an HTML Hex Color Code or not. Print Yes if it is, otherwise print No.
Examples:
Input: str = “#1AFFa1”
Output: YesInput: str = “#F00”
Output: YesInput: str = �”
Output: No
Approach: An HTML Hex Color Code follows the below-mentioned set of rules:
- It starts with the ‘#’ symbol.
- Then it is followed by the letters from a-f, A-F and/or digits from 0-9.
- The length of the hexadecimal color code should be either 6 or 3, excluding ‘#’ symbol.
- For example: #abc, #ABC, #000, #FFF, #000000, #FF0000, #00FF00, #0000FF, #FFFFFF are all valid Hexadecimal color codes.
Now, to solve the above problem follow the below steps:
- Check the string str for the following conditions:
- If the first character is not #, return false.
- If the length is not 3 or 6. If not, return false.
- Now, check for all characters other than the first character that are 0-9, A-F or a-f.
- If all the conditions mentioned above are satisfied, then return true.
- Print answer according to the above observation.
Below is the implementation of the above approach:
CPP
// C++ program for the above approach#include <iostream>using namespace std;// Function to validate // the HTML hexadecimal color code.bool isValidHexaCode(string str){ if (str[0] != '#') return false; if (!(str.length() == 4 or str.length() == 7)) return false; for (int i = 1; i < str.length(); i++) if (!((str[i] >= '0' && str[i] <= 9) || (str[i] >= 'a' && str[i] <= 'f') || (str[i] >= 'A' || str[i] <= 'F'))) return false; return true;}// Driver Codeint main(){ string str = "#1AFFa1"; if (isValidHexaCode(str)) { cout << "Yes" << endl; } else { cout << "No" << endl; } return 0;} |
Java
// Java program for the above approachimport java.util.*;class GFG{ // Function to validate // the HTML hexadecimal color code. static boolean isValidHexaCode(String str) { if (str.charAt(0) != '#') return false; if (!(str.length() == 4 || str.length() == 7)) return false; for (int i = 1; i < str.length(); i++) if (!((str.charAt(i) >= '0' && str.charAt(i) <= 9) || (str.charAt(i) >= 'a' && str.charAt(i) <= 'f') || (str.charAt(i) >= 'A' || str.charAt(i) <= 'F'))) return false; return true; } // Driver code public static void main(String args[]) { String str = "#1AFFa1"; if (isValidHexaCode(str)) { System.out.println("Yes"); } else { System.out.println("No"); } }}// This code is contributed by Samim Hossain Mondal. |
Python3
# python program for the above approach# Function to validate# the HTML hexadecimal color code.def isValidHexaCode(str): if (str[0] != '#'): return False if (not(len(str) == 4 or len(str) == 7)): return False for i in range(1, len(str)): if (not((str[i] >= '0' and str[i] <= '9') or (str[i] >= 'a' and str[i] <= 'f') or (str[i] >= 'A' or str[i] <= 'F'))): return False return True# Driver Codeif __name__ == "__main__": str = "#1AFFa1" if (isValidHexaCode(str)): print("Yes") else: print("No") # This code is contributed by rakeshsahni |
C#
// C# program for the above approachusing System;class GFG{ // Function to validate // the HTML hexadecimal color code. static bool isValidHexaCode(string str) { if (str[0] != '#') return false; if (!(str.Length == 4 || str.Length == 7)) return false; for (int i = 1; i < str.Length; i++) if (!((str[i] >= '0' && str[i] <= 9) || (str[i] >= 'a' && str[i] <= 'f') || (str[i] >= 'A' || str[i] <= 'F'))) return false; return true; } // Driver code public static void Main() { string str = "#1AFFa1"; if (isValidHexaCode(str)) { Console.Write("Yes"); } else { Console.Write("No"); } }}// This code is contributed by Samim Hossain Mondal. |
Javascript
<script> // JavaScript Program to implement // the above approach // Function to validate // the HTML hexadecimal color code. function isValidHexaCode(str) { if (str[0] != '#') return false; if (!(str.length == 4 || str.length == 7)) return false; for (let i = 1; i < str.length; i++) if (!((str[i].charCodeAt(0) <= '0'.charCodeAt(0) && str[i].charCodeAt(0) <= 9) || (str[i].charCodeAt(0) >= 'a'.charCodeAt(0) && str[i].charCodeAt(0) <= 'f'.charCodeAt(0)) || (str[i].charCodeAt(0) >= 'A'.charCodeAt(0) || str[i].charCodeAt(0) <= 'F'.charCodeAt(0)))) return false; return true; } // Driver Code let str = "#1AFFa1"; if (isValidHexaCode(str)) { document.write("Yes" + '<br>'); } else { document.write("No" + '<br>'); } // This code is contributed by Potta Lokesh </script> |
Output
Yes
Time Complexity: O(N)
Auxiliary Space: O(1)
Approach 2: Regex Expression:
In this approach, we have used regex library to define a regular expression pattern to match the HTML hexadecimal color code. The regular expression pattern ^#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$ matches the string that starts with # and followed by either 6 hexadecimal digits or 3 hexadecimal digits. The regex_match function checks if the given string matches the regular expression pattern or not, and returns true if it matches, else false.
Here is the code given below:
C++
#include <iostream>#include <regex>using namespace std;// Function to validate // the HTML hexadecimal color code using regex.bool isValidHexaCode(string str){ regex hexaCode("^#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$"); return regex_match(str, hexaCode);}// Driver Codeint main(){ string str = "#1AFFa1"; if (isValidHexaCode(str)) { cout << "Yes" << endl; } else { cout << "No" << endl; } return 0;} |
Java
import java.util.regex.Pattern;import java.util.regex.Matcher;public class GFG { // Function to check if a given string is a valid hexadecimal color code public static boolean isValidHexaCode(String input) { // Define the regular expression pattern for a valid hexadecimal color code // It matches either a 6-character or 3-character code, preceded by a # Pattern hexaPattern = Pattern.compile("^#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$"); // Create a Matcher object to match the input against the pattern Matcher matcher = hexaPattern.matcher(input); // Return true if the input matches the pattern, otherwise false return matcher.matches(); } public static void main(String[] args) { String input = "#1AFFa1"; if (isValidHexaCode(input)) { System.out.println("Yes"); } else { System.out.println("No"); } }} |
Python3
import redef is_valid_hexa_code(string): hexa_code = re.compile(r'^#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$') return bool(re.match(hexa_code, string))if __name__ == "__main__": string = "#1AFFa1" if is_valid_hexa_code(string): print("Yes") else: print("No") |
C#
using System;using System.Text.RegularExpressions;class GFG{ // Function to validate the HTML hexadecimal color code using regex. static bool IsValidHexaCode(string str) { // Regular expression to match a valid hexadecimal color code. // The pattern "^#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$" checks for: // ^ - Start of the string // # - The string must start with a hash character (#) // ( - Start of the first group // [a-fA-F0-9]{6} - Matches exactly six characters which can be any of a-f, A-F, or 0-9 // | - OR // [a-fA-F0-9]{3} - Matches exactly three characters which can be any of a-f, A-F, or 0-9 // ) - End of the first group // $ - End of the string Regex hexaCode = new Regex(@"^#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$"); // Check if the input string matches the regex pattern. return hexaCode.IsMatch(str); } static void Main() { string str = "#1AFFa1"; if (IsValidHexaCode(str)) { Console.WriteLine("Yes"); } else { Console.WriteLine("No"); } }} |
Javascript
function isValidHexaCode(input) { // Define the regular expression pattern for a valid hexadecimal color code // It matches either a 6-character or 3-character code, preceded by a # var hexaPattern = /^#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$/; // Test the input against the pattern using the test() method return hexaPattern.test(input);}var input = "#1AFFa1";if (isValidHexaCode(input)) { console.log("Yes");} else { console.log("No");} |
Output
Yes
Time Complexity: O(N)
Auxiliary Space: O(1)
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