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 = 5Output:9

All possible sub-strings of length 5 are “geeks”, “eeksf”, “eksfo”,

“ksfor”, “sforg”, “forge”, “orgee”, “rgeek” and “geeks”.Input:str = “jgec”, N = 2Output:3

**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 <bits/stdc++.h>` `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

`<?php` `// PHP implementation of the approach` `// Function to return the count of` `// possible sub-strings of length n` `function` `countSubStr(` `$str` `, ` `$n` `)` `{` ` ` `$len` `= ` `strlen` `(` `$str` `);` ` ` `return` `(` `$len` `- ` `$n` `+ 1);` `}` `// Driver code` `$str` `= ` `"geeksforgeeks"` `;` `$n` `= 5;` `echo` `(countSubStr(` `$str` `, ` `$n` `));` `// This code is contributed by Code_Mech.` `?>` |

## Javascript

`<script>` ` ` `// JavaScript implementation of the approach` ` ` `// Function to return the count of` ` ` `// possible sub-strings of length n` ` ` `function` `countSubStr(str, n) {` ` ` `var` `len = str.length;` ` ` `return` `len - n + 1;` ` ` `}` ` ` `// Driver code` ` ` `var` `str = ` `"geeksforgeeks"` `;` ` ` `var` `n = 5;` ` ` `document.write(countSubStr(str, n));` `</script>` |

**Output:**

9

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the **DSA Self Paced Course** at a student-friendly price and become industry ready. To complete your preparation from learning a language to DS Algo and many more, please refer **Complete Interview Preparation Course****.**

In case you wish to attend live classes with industry experts, please refer **DSA Live Classes**