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Count of sub-strings of length n possible from the given string
• Last Updated : 07 May, 2021

Given a string str and an integer N, the task is to find the number of possible sub-strings of length N.
Examples:

Input: str = “geeksforgeeks”, n = 5
Output:
All possible sub-strings of length 5 are “geeks”, “eeksf”, “eksfo”,
“ksfor”, “sforg”, “forge”, “orgee”, “rgeek” and “geeks”.
Input: str = “jgec”, N = 2
Output:

Approach: The count of sub-strings of length n will always be len – n + 1 where len is the length of the given string. For example, if str = “geeksforgeeks” and n = 5 then the count of sub-strings having length 5 will be “geeks”, “eeksf”, “eksfo”, “ksfor”, “sforg”, “forge”, “orgee”, “rgeek” and “geeks” which is len – n + 1 = 13 – 5 + 1 = 9.
Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach``#include ``using` `namespace` `std;` `// Function to return the count of``// possible sub-strings of length n``int` `countSubStr(string str, ``int` `n)``{``    ``int` `len = str.length();``    ``return` `(len - n + 1);``}` `// Driver code``int` `main()``{``    ``string str = ``"geeksforgeeks"``;``    ``int` `n = 5;` `    ``cout << countSubStr(str, n);` `    ``return` `0;``}`

## Java

 `// Java implementation of the approach``import` `java.util.*;` `class` `GFG``{` `// Function to return the count of``// possible sub-strings of length n``static` `int` `countSubStr(String str, ``int` `n)``{``    ``int` `len = str.length();``    ``return` `(len - n + ``1``);``}` `// Driver code``public` `static` `void` `main(String args[])``{``    ``String str = ``"geeksforgeeks"``;``    ``int` `n = ``5``;` `    ``System.out.print(countSubStr(str, n));``}``}` `// This code is contributed by mohit kumar 29`

## Python3

 `# Python3 implementation of the approach` `# Function to return the count of``# possible sub-strings of length n``def` `countSubStr(string, n) :` `    ``length ``=` `len``(string);``    ``return` `(length ``-` `n ``+` `1``);` `# Driver code``if` `__name__ ``=``=` `"__main__"` `:` `    ``string ``=` `"geeksforgeeks"``;``    ``n ``=` `5``;` `    ``print``(countSubStr(string, n));``    ` `# This code is contributed by Ryuga`

## C#

 `// C# implementation of the approach``using` `System;` `class` `GFG``{` `// Function to return the count of``// possible sub-strings of length n``static` `int` `countSubStr(``string` `str, ``int` `n)``{``    ``int` `len = str.Length;``    ``return` `(len - n + 1);``}` `// Driver code``public` `static` `void` `Main()``{``    ``string` `str = ``"geeksforgeeks"``;``    ``int` `n = 5;` `    ``Console.WriteLine(countSubStr(str, n));``}``}` `// This code is contributed by Code_Mech.`

## PHP

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## Javascript

 ``
Output:
`9`

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