# Change all even bits in a number to 0

Given a number, change all bits at even positions to 0.

**Examples: **

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 experts, please refer **DSA Live Classes for Working Professionals **and **Competitive Programming Live for Students**.

Input : 30 Output : 10 Binary representation of11110. Bits at Even positions are highlighted. After making all of them 0, we get01010Input : 10 Output : 10

**Method 1 (Bit Traversal)**

The idea is to traverse through all even bits. We accumulate all powers of 2 in a number to subtract. Finally we subtract the accumulated value from n to obtain the result.

## C++

`// C++ program to change even` `// bits to 0.` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Returns modified number with` `// all even bits 0.` `int` `changeEvenBits(` `int` `n)` `{` ` ` `// To store sum of bits` ` ` `// at even positions.` ` ` `int` `to_subtract = 0;` ` ` `// To store bits to shift` ` ` `int` `m = 0;` ` ` `// One by one put all even` ` ` `// bits to end` ` ` `for` `(` `int` `x = n; x; x >>= 2) {` ` ` `// If current last bit` ` ` `// is set, add it to ans` ` ` `if` `(x & 1)` ` ` `to_subtract += (1 << m);` ` ` `// Next shift position` ` ` `m += 2;` ` ` `}` ` ` `return` `n - to_subtract;` `}` `// Driver code` `int` `main()` `{` ` ` `int` `n = 30;` ` ` `cout << changeEvenBits(n) << endl;` ` ` `return` `0;` `}` |

## Java

`// Java program to change even` `// bits to 0.` `import` `java.util.*;` `class` `GFG {` ` ` `// Returns modified number with` ` ` `// all even bits 0.` ` ` `static` `int` `changeEvenBits(` `int` `n)` ` ` `{` ` ` `// To store sum of bits` ` ` `// at even positions.` ` ` `int` `to_subtract = ` `0` `;` ` ` `// To store bits to shift` ` ` `int` `m = ` `0` `;` ` ` `// One by one put all even` ` ` `// bits to end` ` ` `for` `(` `int` `x = n; x > ` `0` `; x >>= ` `2` `) {` ` ` `// If current last bit` ` ` `// is set, add it to ans` ` ` `if` `((x & ` `1` `) > ` `0` `)` ` ` `to_subtract += (` `1` `<< m);` ` ` `// Next shift position` ` ` `m += ` `2` `;` ` ` `}` ` ` `return` `n - to_subtract;` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `main(String[] args)` ` ` `{` ` ` `int` `n = ` `30` `;` ` ` `System.out.println(changeEvenBits(n));` ` ` `}` `}` `/* This code is contributed by Mr. Somesh Awasthi */` |

## Python

`# Python program to change even` `# bits to 0.` `# Returns modified number with` `# all even bits 0.` `def` `changeEvenBits(n):` ` ` `# To store sum of bits` ` ` `# at even positions.` ` ` `to_subtract ` `=` `0` ` ` `# To store bits to shift` ` ` `m ` `=` `0` ` ` `# One by one put all even` ` ` `# bits to end` ` ` `x ` `=` `n` ` ` `while` `(x):` ` ` `# If current last bit` ` ` `# is set, add it to ans` ` ` `if` `(x & ` `1` `):` ` ` `to_subtract ` `+` `=` `(` `1` `<< m)` ` ` `# Next shift position` ` ` `m ` `+` `=` `2` ` ` `x >>` `=` `2` ` ` `return` `n ` `-` `to_subtract` `# Driver code` `n ` `=` `30` `print` `changeEvenBits(n)` `# This code is contributed by Sachin Bisht` |

## C#

`// C# program to change even` `// bits to 0.` `using` `System;` `class` `GFG {` ` ` ` ` `// Returns modified number with` ` ` `// all even bits 0.` ` ` `static` `int` `changeEvenBits(` `int` `n)` ` ` `{` ` ` ` ` `// To store sum of bits` ` ` `// at even positions.` ` ` `int` `to_subtract = 0;` ` ` ` ` `// To store bits to shift` ` ` `int` `m = 0;` ` ` ` ` `// One by one put all even` ` ` `// bits to end` ` ` `for` `(` `int` `x = n; x > 0; x >>= 2)` ` ` `{` ` ` ` ` `// If current last bit` ` ` `// is set, add it to ans` ` ` `if` `((x & 1) > 0)` ` ` `to_subtract += (1 << m);` ` ` ` ` `// Next shift position` ` ` `m += 2;` ` ` `}` ` ` ` ` `return` `n - to_subtract;` ` ` `}` ` ` ` ` `// Driver code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` `int` `n = 30;` ` ` ` ` `Console.Write(changeEvenBits(n));` ` ` `}` `}` `// This code is contributed by nitin mittal.` |

## PHP

`<?php` `// PHP program to change even` `// bits to 0.` `// Returns modified number with` `// all even bits 0.` `function` `changeEvenBits(` `$n` `)` `{` ` ` ` ` `// To store sum of bits` ` ` `// at even positions.` ` ` `$to_subtract` `= 0;` ` ` `// To store bits to shift` ` ` `$m` `= 0;` ` ` `// One by one put all even` ` ` `// bits to end` ` ` `for` `(` `$x` `= ` `$n` `; ` `$x` `; ` `$x` `>>= 2)` ` ` `{` ` ` ` ` `// If current last bit` ` ` `// is set, add it to ans` ` ` `if` `(` `$x` `& 1)` ` ` `$to_subtract` `+= (1 << ` `$m` `);` ` ` `// Next shift position` ` ` `$m` `+= 2;` ` ` `}` ` ` `return` `$n` `- ` `$to_subtract` `;` `}` ` ` `// Driver code` ` ` `$n` `= 30;` ` ` `echo` `changeEvenBits(` `$n` `) ;` `// This code is contributed by nitin mittal` `?>` |

## Javascript

`<script>` `// js program to change even` `// bits to 0.` `// Returns modified number with` `// all even bits 0.` `function` `changeEvenBits(n)` `{` ` ` ` ` `// To store sum of bits` ` ` `// at even positions.` ` ` `let to_subtract = 0;` ` ` `// To store bits to shift` ` ` `let m = 0;` ` ` `// One by one put all even` ` ` `// bits to end` ` ` `for` `(x = n; x; x >>= 2)` ` ` `{` ` ` ` ` `// If current last bit` ` ` `// is set, add it to ans` ` ` `if` `(x & 1)` ` ` `to_subtract += (1 << m);` ` ` `// Next shift position` ` ` `m += 2;` ` ` `}` ` ` `return` `n - to_subtract;` `}` ` ` `// Driver code` ` ` `n = 30;` ` ` `document.write( changeEvenBits(n) );` `// This code is contributed by sravan kumar` `</script>` |

**Output**

10

**Method 2: (Bit masking)**

## C++

`#include <bits/stdc++.h>` `using` `namespace` `std;` `int` `convertEvenBitToOne(` `int` `n) { ` `return` `(n & 0xaaaaaaaa); }` `int` `main()` `{` ` ` `int` `n = 30;` ` ` `cout << convertEvenBitToOne(n);` ` ` `return` `0;` `}` |

## Java

`// Java program using Bitmask to` `// Change all even bits in a` `// number to 0` `import` `java.io.*;` `class` `GFG {` ` ` `static` `int` `convertEvenBitToOne(` `int` `n)` ` ` `{` ` ` `return` `(n & ` `0xaaaaaaaa` `);` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `main(String[] args)` ` ` `{` ` ` `int` `n = ` `30` `;` ` ` `System.out.println(convertEvenBitToOne(n));` ` ` `}` `}` `// This code is contributed by anuj_67.` |

## Python

`def` `convertEvenBitToOne(n):` ` ` `return` `(n & ` `0xaaaaaaaa` `)` `# Driver code` `n ` `=` `30` `print` `convertEvenBitToOne(n)` `# This code is contributed by Sachin Bisht` |

## C#

`// C# program using Bitmask to` `// Change all even bits in a` `// number to 0` `using` `System;` `class` `GFG {` ` ` `static` `long` `convertEvenBitToOne(` `int` `n)` ` ` `{` ` ` `return` `(n & 0xaaaaaaaa);` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` `int` `n = 30;` ` ` `Console.WriteLine(convertEvenBitToOne(n));` ` ` `}` `}` `// This code is contributed by anuj_67.` |

## PHP

`<?php` `// PHP program using Bitmask to` `// Change all even bits in a` `// number to 0` `function` `convertEvenBitToOne(` `$n` `)` `{` ` ` `return` `(` `$n` `& 0xaaaaaaaa);` `}` `// Driver Code` `$n` `= 30;` `echo` `convertEvenBitToOne(` `$n` `);` `// This code is contributed by anuj_67.` `?>` |

## Javascript

`<script>` `// java script program using Bitmask to` `// Change all even bits in a` `// number to 0` `function` `convertEvenBitToOne(n)` `{` ` ` `return` `(n & 0xaaaaaaaa);` `}` `// Driver Code` `n = 30;` `document.write(convertEvenBitToOne(n));` `// This code is contributed by sravan kumar` `</script>` |

**Output**

10

This article is contributed by **RISHABH RAJ JHA **. 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.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.