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Program to check if input is an integer or a string
• Difficulty Level : Basic
• Last Updated : 06 Oct, 2020

Write a function to check whether a given input is an integer or a string.

Definition of an integer :

```Every element should be a valid digit, i.e '0-9'.
```

Definition of a string :

```Any one element should be an invalid digit, i.e any symbol other than '0-9'.
```

Examples:

```Input : 127
Output : Integer
Explanation : All digits are in the range '0-9'.

Input : 199.7
Output : String
Explanation : A dot is present.

Input : 122B
Output : String
Explanation : A alphabet is present.
```

The idea is to use isdigit() function and is_numeric() function..

Below is the implementation of the above idea.

## C++

 `// CPP program to check if a given string``// is a valid integer``#include ``using` `namespace` `std;` `// Returns true if s is a number else false``bool` `isNumber(string s)``{``    ``for` `(``int` `i = 0; i < s.length(); i++)``        ``if` `(``isdigit``(s[i]) == ``false``)``            ``return` `false``;` `    ``return` `true``;``}` `// Driver code``int` `main()``{``    ``// Saving the input in a string``    ``string str = ``"6790"``;` `    ``// Function returns 1 if all elements``    ``// are in range '0-9'``    ``if` `(isNumber(str))``        ``cout << ``"Integer"``;` `    ``// Function returns 0 if the input is``    ``// not an integer``    ``else``        ``cout << ``"String"``;``}`

## Java

 `// Java program to check if a given``// string is a valid integer``import` `java.io.*;` `public` `class` `GFG {` `    ``// Returns true if s is``    ``// a number else false``    ``static` `boolean` `isNumber(String s)``    ``{``        ``for` `(``int` `i = ``0``; i < s.length(); i++)``            ``if` `(Character.isDigit(s.charAt(i)) == ``false``)``                ``return` `false``;` `        ``return` `true``;``    ``}` `    ``// Driver code``    ``static` `public` `void` `main(String[] args)``    ``{``        ``// Saving the input in a string``        ``String str = ``"6790"``;` `        ``// Function returns 1 if all elements``        ``// are in range '0 - 9'``        ``if` `(isNumber(str))``            ``System.out.println(``"Integer"``);` `        ``// Function returns 0 if the``        ``// input is not an integer``        ``else``            ``System.out.println(``"String"``);``    ``}``}` `// This code is contributed by vt_m.`

## Python 3

 `# Python 3 program to check if a given string``# is a valid integer` `# This function Returns true if``# s is a number else false``def` `isNumber(s):` `    ``for` `i ``in` `range``(``len``(s)):``        ``if` `s[i].isdigit() !``=` `True``:``            ``return` `False` `    ``return` `True`  `# Driver code``if` `__name__ ``=``=` `"__main__"``:` `    ``# Store the input in a str variable``    ``str` `=` `"6790"` `    ``# Function Call``    ``if` `isNumber(``str``):``        ``print``(``"Integer"``)` `    ``else``:``        ``print``(``"String"``)` `# This code is contributed by ANKITRAI1`

## C#

 `// C# program to check if a given``// string is a valid integer``using` `System;` `public` `class` `GFG {` `    ``// Returns true if s is a``    ``// number else false``    ``static` `bool` `isNumber(``string` `s)``    ``{``        ``for` `(``int` `i = 0; i < s.Length; i++)``            ``if` `(``char``.IsDigit(s[i]) == ``false``)``                ``return` `false``;` `        ``return` `true``;``    ``}` `    ``// Driver code``    ``static` `public` `void` `Main(String[] args)``    ``{` `        ``// Saving the input in a string``        ``string` `str = ``"6790"``;` `        ``// Function returns 1 if all elements``        ``// are in range '0 - 9'``        ``if` `(isNumber(str))``            ``Console.WriteLine(``"Integer"``);` `        ``// Function returns 0 if the``        ``// input is not an integer``        ``else``            ``Console.WriteLine(``"String"``);``    ``}``}` `// This code is contributed by vt_m.`

## PHP

 ``
Output
`Integer`

Using special Python built-in type() function:

type() is a built-in function provided by python . type() takes object as parameter and returns its class type as its name says.

Below is the implementation of the above idea:

## Python3

 `# Python program to find``# whether the user input``# is int or string type` `# Function to determine whether``# the user input is string or``# integer type``def` `isNumber(x):``    ``if` `type``(x) ``=``=` `int``:``         ``return` `True``    ``else``:``         ``return` `False`  `# Driver Code``input1 ``=` `122``input2 ``=` `'122'` `# Function Call` `# for input1``if` `isNumber(input1):``    ``print``(``"Integer"``)``else``:``    ``print``(``"String"``)` `# for input2``if` `isNumber(input2):``    ``print``(``"Integer"``)``else``:``    ``print``(``"String"``)`
Output
```Integer
String
```

This article is contributed by Rohit Thapliyal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.