Given string str, the task is to check whether the string is alphanumeric or not by using Regular Expression.
An alphanumeric string is a string that contains only alphabets from a-z, A-Z and some numbers from 0-9.
Examples:
Input: str = “GeeksforGeeks123”
Output: true
Explanation:
This string contains all the alphabets from a-z, A-Z, and the number from 0-9. Therefore, it is an alphanumeric string.
Input: str = “GeeksforGeeks”
Output: false
Explanation:
This string contains all the alphabets from a-z, A-Z, but doesn’t contain any number from 0-9. Therefore, it is not an alphanumeric string.
Input: str = “GeeksforGeeks123@#”
Output: false
Explanation:
This string contains all the alphabets from a-z, A-Z, and the number from 0-9 along with some special symbols. Therefore, it is not an alphanumeric string.
Approach: This problem can be solved by using Regular Expression.
- Get the string.
- Create a regular expression to check string is alphanumeric or not as mentioned below:
regex = "^(?=.*[a-zA-Z])(?=.*[0-9])[A-Za-z0-9]+$";
- Where:
- ^ represents the starting of the string
- (?=.*[a-zA-Z]) represents the alphabets from a-z, A-Z
- (?=.*[0-9]) represents any number from 0-9
- [A-Za-z0-9] represents whether everything is either alphabetical or digit
- + represents one or more times
- $ represents the ending of the string
- Match the given string with the regex, in Java, this can be done by using Pattern.matcher()
- Return true if the string matches with the given regex, else return false
Below is the implementation of the above approach.
// C++ program to check // String is alphanumeric or not using Regular Expression #include <iostream> #include <regex> using namespace std;
// Function to validate the // String is alphanumeric or not using Regular Expression bool isAlphaNumeric(string str) {
// Regex to check valid alphanumeric String. const regex pattern( "^(?=.*[a-zA-Z])(?=.*[0-9])[A-Za-z0-9]+$" );
// If the string // is empty return false if (str.empty())
{
return false ;
}
// Return true if the String // matched the ReGex if (regex_match(str, pattern))
{ return true ;;
} else { return false ;
} } // Driver Code int main()
{ // Test Case 1:
string str1= "GeeksforGeeks123" ;
cout <<isAlphaNumeric(str1) << endl; // Test Case 2: string str2= "GeeksforGeeks" ;
cout << isAlphaNumeric(str2) << endl;
// Test Case 3: string str3= "GeeksforGeeks123@#" ;
cout << isAlphaNumeric(str3) << endl; // Test Case 4: string str4= "123" ;
cout << isAlphaNumeric(str4) << endl; //Test Case 5: string str5= "@#" ;
cout << isAlphaNumeric(str5) << endl; return 0;
} //This Code is contributed by Rahul Chauhan |
// Java program to check string is // alphanumeric or not using Regular Expression. import java.util.regex.*;
class GFG {
// Function to check string is alphanumeric or not
public static boolean isAlphaNumeric(String str)
{
// Regex to check string is alphanumeric or not.
String regex = "^(?=.*[a-zA-Z])(?=.*[0-9])[A-Za-z0-9]+$" ;
// Compile the ReGex
Pattern p = Pattern.compile(regex);
// If the string is empty
// return false
if (str == null ) {
return false ;
}
// Pattern class contains matcher() method
// to find matching between given string
// and regular expression.
Matcher m = p.matcher(str);
// Return if the string
// matched the ReGex
return m.matches();
}
// Driver Code.
public static void main(String args[])
{
// Test Case 1:
String str1 = "GeeksforGeeks123" ;
System.out.println(
str1 + ": "
+ isAlphaNumeric(str1));
// Test Case 2:
String str2 = "GeeksforGeeks" ;
System.out.println(
str2 + ": "
+ isAlphaNumeric(str2));
// Test Case 3:
String str3 = "GeeksforGeeks123@#" ;
System.out.println(
str3 + ": "
+ isAlphaNumeric(str3));
// Test Case 4:
String str4 = "123" ;
System.out.println(
str4 + ": "
+ isAlphaNumeric(str4));
// Test Case 5:
String str5 = "@#" ;
System.out.println(
str5 + ": "
+ isAlphaNumeric(str5));
}
} |
# Python3 program to check # string is alphanumeric or # not using Regular Expression. import re
# Function to check string # is alphanumeric or not def isAlphaNumeric( str ):
# Regex to check string is
# alphanumeric or not.
regex = "^(?=.*[a-zA-Z])(?=.*[0-9])[A-Za-z0-9]+$"
# Compile the ReGex
p = re. compile (regex)
# If the string is empty
# return false
if ( str = = None ):
return False
# Return if the string
# matched the ReGex
if (re.search(p, str )):
return True
else :
return False
# Driver Code # Test Case 1: str1 = "GeeksforGeeks123"
print (str1, ":" ,
isAlphaNumeric(str1))
# Test Case 2: str2 = "GeeksforGeeks"
print (str2, ":" ,
isAlphaNumeric(str2))
# Test Case 3: str3 = "GeeksforGeeks123@#"
print (str3, ":" ,
isAlphaNumeric(str3))
# Test Case 4: str4 = "123"
print (str4, ":" ,
isAlphaNumeric(str4))
# Test Case 5: str5 = "@#"
print (str5, ":" ,
isAlphaNumeric(str5))
# This code is contributed by avanitrachhadiya2155 |
// C# program to check // String is alphanumeric or not using Regular Expression using System;
using System.Text.RegularExpressions;
class GFG
{ // Main Method
static void Main( string [] args)
{
// Input strings to Match
// String is alphanumeric or not
string [] str={ "GeeksforGeeks123" , "GeeksforGeeks" ,
"GeeksforGeeks123@#" , "123" ,
"@#" };
foreach ( string s in str) {
Console.WriteLine( isAlphaNumeric(s) ? "true" : "false" );
}
Console.ReadKey(); }
// method containing the regex
public static bool isAlphaNumeric( string str)
{
string strRegex = @"^(?=.*[a-zA-Z])(?=.*[0-9])[A-Za-z0-9]+$" ;
Regex re = new Regex(strRegex);
if (re.IsMatch(str))
return ( true );
else
return ( false );
}
} // This code is contributed by Rahul Chauhan |
// Javascript program to check // String is alphanumeric or not using Regular Expression // Function to validate the // string function isAlphaNumeric(str) {
// Regex to check valid
// alphanumeric string
let regex = new RegExp(/^(?=.*[a-zA-Z])(?=.*[0-9])[A-Za-z0-9]+$/);
// if str
// is empty return false
if (str == null ) {
return "false" ;
}
// Return true if the str
// matched the ReGex
if (regex.test(str) == true ) {
return "true" ;
}
else {
return "false" ;
}
} // Driver Code // Test Case 1: let str1 = "GeeksforGeeks123" ;
console.log(isAlphaNumeric(str1)); // Test Case 2: let str2 = "GeeksforGeeks" ;
console.log(isAlphaNumeric(str2)); // Test Case 3: let str3 = "GeeksforGeeks123@#" ;
console.log(isAlphaNumeric(str3)); // Test Case 4: let str4 = "#123" ;
console.log(isAlphaNumeric(str4)); // Test Case 5: let str5 = "#@#" ;
console.log(isAlphaNumeric(str5)); // This code is contributed by Rahul Chauhan |
GeeksforGeeks123: true GeeksforGeeks: false GeeksforGeeks123@#: false 123: false @#: false