# Validating UPI IDs using Regular Expressions

• Last Updated : 14 Dec, 2022

Given some UPI IDs, the task is to check if they are valid or not using regular expressions. Rules for the valid UPI ID:

• UPI ID is an alphanumeric String i.e., formed using digits(0-9), alphabets (A-Z and a-z), and other special characters.
• It must contain ‘@’.
• It should not contain whitespace.
• It may or may not contain a dot (.) or hyphen (-).

UPI stands for Unified Payments Interface (UPI).UPI IDs are unique IDs given to each customer.

Examples :

Input: str = â€ť9136812895@yblâ€ł
Output: True

Input: str = â€ťMH05DL9023 â€ť
Output: false
Explanation: It does not contain the “@” symbol.

Input: str = â€ťViratKohli101@paytmâ€ł
Output: true

Input: str =â€ťrahul.12chauhan1998-1@okiciciâ€ł
Output: true

Input: str = â€ť1234567890@upi123456â€ł
Output: true

Input: str = â€ťAkanksha  @ybl â€ť
Output: false
Explanation: It contains a whitespace.

Approach: The problem can be solved based on the following idea:

Create a regex pattern to validate the number as written below:
regex=â€ť^[a-zA-Z0-9.-]{2, 256}@[a-zA-Z][a-zA-Z]{2, 64}\$â€ť

^ : Beginning of the string.
[] Character set :Match any character  in the set.
[a-zA-Z0-9.-] : Match any character in the range a-z, A-Z, 0-9, hyphen(-), dot(.).
{2, 256} Quantifier: Match between 2 and 256 of the preceding items.
\$: End of the string

Follow the below steps to implement the idea:

• Create regex expression for UPI ID.
• Use Pattern class to compile the regex formed.
•  Use the matcher function to check whether the UPI id is valid or not.
• If it is valid, return true. Otherwise, return false.

Below is the implementation of the above approach.

## C++

```// C++ program to validate the
// UPI ID using Regular
// Expression

#include <bits/stdc++.h>
#include <regex>
using namespace std;

// Function to validate the
// upi_Id Code
string isValidUpi(string upi_Id)
{
// Regex to check valid upi_Id Code
const regex pattern(
"^[a-zA-Z0-9.-]{2, 256}@[a-zA-Z][a-zA-Z]{2, 64}\$");

// If the upi_Id Code
// is empty return false
if (upi_Id.empty()) {
return "false";
}

// Return true if the upi_Id Code
// matched the ReGex
if (regex_match(upi_Id, pattern)) {
return "true";
}
else {
return "false";
}
}

// Driver Code
int main()
{
// Test Case 1:
string str1 = "9136812895@ybl";
cout << isValidUpi(str1) << endl;

// Test Case 2:
string str2 = "rahul.12chauhan1998-1@okicici";
cout << isValidUpi(str2) << endl;

// Test Case 3:
string str3 = "BNZAA2318JM";
cout << isValidUpi(str3) << endl;

// Test Case 4:
string str4 = "934517865";
cout << isValidUpi(str4) << endl;

// Test Case 5:
string str5 = "ViratKohli101@paytm";
cout << isValidUpi(str5) << endl;

// Test Case 6:
string str6 = "Akanksha  @ybl";
cout << isValidUpi(str6) << endl;

return 0;
}```

## Java

```// Java program to validate the
// UPI ID using Regular Expression

import java.util.regex.*;

class GFG {
// Function to validate the
// UPI ID(For India Country Only)
public static boolean isValidUpi(String upi_Id)
{

// Regex to check valid upi_Id Code
String regex
= "^[a-zA-Z0-9.-]{2, 256}@[a-zA-Z][a-zA-Z]{2, 64}\$";

// Compile the ReGex
Pattern p = Pattern.compile(regex);

// If the upi_Id Code
// is empty return false
if (upi_Id == null) {
return false;
}

// Pattern class contains matcher()
// method to find matching between
// given MICR Code using regex
Matcher m = p.matcher(upi_Id);

// Return if the upi_Id Code
// matched the ReGex
return m.matches();
}

// Driver Code.
public static void main(String args[])
{

// Test Case 1:
String str1 = "9136812895@ybl";
System.out.println(isValidUpi(str1));

// Test Case 2:
String str2 = "rahul.12chauhan1998-1@okicici";
System.out.println(isValidUpi(str2));

// Test Case 3:
String str3 = "BNZAA2318JM";
System.out.println(isValidUpi(str3));

// Test Case 4:
String str4 = "934517865";
System.out.println(isValidUpi(str4));

// Test Case 5:
String str5 = "ViratKohli101@paytm";
System.out.println(isValidUpi(str5));

// Test Case 6:
String str6 = "Akanksha  @ybl";
System.out.println(isValidUpi(str6));
}
}```

## Python3

```# Python3 program to validate
# UPI ID  using Regular Expression

import re

# Function to validate
# UPI ID(For India Country Only)
def isValidUpi(str):

# Regex to check valid UPI ID
regex = "^[a-zA-Z0-9.-]{2, 256}@[a-zA-Z][a-zA-Z]{2, 64}\$"

# 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
if __name__ == '__main__':

# Test Case 1:
str1 = "9136812895@ybl"
print(isValidUpi(str1))

# Test Case 2:
str2 = "rahul.12chauhan1998-1@okicici"
print(isValidUpi(str2))

# Test Case 3:
str3 = "Rahul 1998"
print(isValidUpi(str3))

# Test Case 4:
str4 = "934517865"
print(isValidUpi(str4))

# Test Case 5:
str5 = "ViratKohli101@paytm"
print(isValidUpi(str5))

# Test Case 6:
str6 = "Akanksha  @ybl"
print(isValidUpi(str6))```

## C#

```// C# program to validate the
// UPI ID using Regular Expression
using System;
using System.Text.RegularExpressions;

public class GFG
{

// Function to validate the
// UPI ID(For India Country Only)
public static bool isValidUpi(string upi_Id)
{

// Regex to check valid upi_Id Code
string regex
= "^[a-zA-Z0-9.-]{2, 256}@[a-zA-Z][a-zA-Z]{2, 64}\$";

// Compile the ReGex
Regex p = new Regex(regex);

// If the upi_Id Code
// is empty return false
if (upi_Id == null) {
return false;
}

// Pattern class contains matcher()
// method to find matching between
// given MICR Code using regex
Match m = p.Match(upi_Id);

// Return if the upi_Id Code
// matched the ReGex
return m.Success;
}

// Driver Code.
public static void Main()
{

// Test Case 1:
string str1 = "9136812895@ybl";
Console.WriteLine(isValidUpi(str1));

// Test Case 2:
string str2 = "rahul.12chauhan1998-1@okicici";
Console.WriteLine(isValidUpi(str2));

// Test Case 3:
string str3 = "BNZAA2318JM";
Console.WriteLine(isValidUpi(str3));

// Test Case 4:
string str4 = "934517865";
Console.WriteLine(isValidUpi(str4));

// Test Case 5:
string str5 = "ViratKohli101@paytm";
Console.WriteLine(isValidUpi(str5));

// Test Case 6:
string str6 = "Akanksha @ybl";
Console.WriteLine(isValidUpi(str6));
}
}

// This code is contributed by Pushpesh Raj.
```

## Javascript

```// Javascript program to validate
// UPI ID  using Regular Expression

// Function to validate the
// upi_Id Code
function isValid_UPI_ID(upi_Id) {
// Regex to check valid
// upi_Id
let regex = new RegExp(/^[a-zA-Z0-9.-]{2, 256}@[a-zA-Z][a-zA-Z]{2, 64}\$/);

// upi_Id
// is empty return false
if (upi_Id == null) {
return "false";
}

// Return true if the upi_Id
// matched the ReGex
if (regex.test(upi_Id) == true) {
return "true";
}
else {
return "false";
}
}

// Driver Code
// Test Case 1:
let str1 = "9136812895@ybl";
console.log(isValid_UPI_ID(str1));

// Test Case 2:
let str2 = "rahul.12chauhan1998-1@okicici";
console.log(isValid_UPI_ID(str2));

// Test Case 3:
let str3 = "BNZAA2318JM";
console.log(isValid_UPI_ID(str3));

// Test Case 4:
let str4 = "MH 05 S 9954";
console.log(isValid_UPI_ID(str4));

// Test Case 5:
let str5 = "ViratKohli101@paytm";
console.log(isValid_UPI_ID(str5));

// Test Case 6:
let str6 = "Akanksha  @ybl";
console.log(isValid_UPI_ID(str6));
```
Output

```true
true
false
false
true
false```

Time Complexity: O(N) for each testcase, where N is the length of the given string.
Auxiliary Space: O(1)

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