Check a string to see if all characters are hexadecimal values

Question

What is the most efficient way in C# 2.0 to check each character in a string and return true if they are all valid hexadecimal characters and false otherwise?

Example

void Test() {     OnlyHexInString("123ABC"); // Returns true     OnlyHexInString("123def"); // Returns true     OnlyHexInString("123g"); // Returns false }  bool OnlyHexInString(string text) {     // Most efficient algorithm to check each digit in C# 2.0 goes here } 

Answer 1

Something like this:

(I don't know C# so I'm not sure how to loop through the chars of a string.)

loop through the chars {     bool is_hex_char = (current_char >= '0' && current_char <= '9') ||                        (current_char >= 'a' && current_char <= 'f') ||                        (current_char >= 'A' && current_char <= 'F');      if (!is_hex_char) {         return false;     } }  return true; 

Code for Logic Above

private bool IsHex(IEnumerable<char> chars) {     bool isHex;      foreach(var c in chars)     {         isHex = ((c >= '0' && c <= '9') ||                   (c >= 'a' && c <= 'f') ||                   (c >= 'A' && c <= 'F'));          if(!isHex)             return false;     }     return true; } 

Answer 2

public bool OnlyHexInString(string test) {     // For C-style hex notation (0xFF) you can use @"\A\b(0[xX])?[0-9a-fA-F]+\b\Z"     return System.Text.RegularExpressions.Regex.IsMatch(test, @"\A\b[0-9a-fA-F]+\b\Z"); }