# Swap two nibbles in a byte

A nibble is a four-bit aggregation, or half an octet. There are two nibbles in a byte.
Given a byte, swap the two nibbles in it. For example 100 is be represented as 01100100 in a byte (or 8 bits). The two nibbles are (0110) and (0100). If we swap the two nibbles, we get 01000110 which is 70 in decimal.

## Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

To swap the nibbles, we can use bitwise &, bitwise ” operators. A byte can be represented using a unsigned char in C as size of char is 1 byte in a typical C compiler.
Below is the implementation of above idea.

## C++

 `// C++ program to swap two ` `// nibbles in a byte ` `#include ` `using` `namespace` `std; ` ` `  `int` `swapNibbles(``int` `x) ` `{ ` `    ``return` `( (x & 0x0F) << 4 | (x & 0xF0) >> 4 ); ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `x = 100; ` `    ``cout << swapNibbles(x); ` `    ``return` `0; ` `} ` ` `  `//This code is contributed by Shivi_Aggarwal `

## C

 `#include ` ` `  `unsigned ``char` `swapNibbles(unsigned ``char` `x) ` `{ ` `    ``return` `( (x & 0x0F)<<4 | (x & 0xF0)>>4 ); ` `} ` ` `  `int` `main() ` `{ ` `    ``unsigned ``char` `x = 100; ` `    ``printf``(``"%u"``, swapNibbles(x)); ` `    ``return` `0; ` `}`

## Java

 `// Java program to swap two ` `// nibbles in a byte ` ` `  `class` `GFG { ` `     `  `static` `int` `swapNibbles(``int` `x) ` `{ ` `    ``return` `((x & ``0x0F``) << ``4` `| (x & ``0xF0``) >> ``4``); ` `} ` ` `  `// Driver code ` `public` `static` `void` `main(String arg[]) ` `{ ` `    ``int` `x = ``100``; ` `    ``System.out.print(swapNibbles(x)); ` `} ` `} ` ` `  `// This code is contributed by Anant Agarwal. `

## Python3

 `# python program Swap ` `# two nibbles in a byte ` ` `  `def` `swapNibbles(x): ` `    ``return` `( (x & ``0x0F``)<<``4` `| (x & ``0xF0``)>>``4` `) ` ` `  `# Driver code ` ` `  `x ``=` `100` `print``(swapNibbles(x)) ` ` `  `# This code is contributed ` `# by Anant Agarwal. `

## C#

 `// C# program to swap two ` `// nibbles in a byte ` `using` `System; ` ` `  `class` `GFG { ` ` `  `// Function for swapping     ` `static` `int` `swapNibbles(``int` `x) ` `{ ` `    ``return` `((x & 0x0F) << 4 |  ` `            ``(x & 0xF0) >> 4); ` `} ` ` `  `// Driver code ` `public` `static` `void` `Main() ` `{ ` `    ``int` `x = 100; ` `    ``Console.Write(swapNibbles(x)); ` `} ` `} ` ` `  `// This code is contributed by Nitin Mittal. `

## PHP

 `> 4 ); ` `} ` ` `  `    ``// Driver Code ` `    ``\$x` `= 100; ` `    ``echo` `swapNibbles(``\$x``); ` ` `  `// This Code is Contributed by Ajit ` `?> `

Output:

`70`

Explanation:
100 is 01100100 in binary. The operation can be split mainly in two parts
1) The expression “x & 0x0F” gives us last 4 bits of x. For x = 100, the result is 00000100. Using bitwise ‘<<' operator, we shift the last four bits to the left 4 times and make the new last four bits as 0. The result after shift is 01000000.

2) The expression “x & 0xF0” gives us first four bits of x. For x = 100, the result is 01100000. Using bitwise ‘>>’ operator, we shift the digit to the right 4 times and make the first four bits as 0. The result after shift is 00000110.

At the end we use the bitwise OR ‘|’ operation of the two expressions explained above. The OR operator places first nibble to the end and last nibble to first. For x = 100, the value of (01000000) OR (00000110) gives the result 01000110 which is equal to 70 in decimal.

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