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How to calculate log base 2 of an Integer in Java?

• Difficulty Level : Easy
• Last Updated : 11 Mar, 2022

Given an integer N, the task is to calculate its log to the base 2, i.e. log2 N in Java.

Examples:

```Input: N = 2
Output: 1

Input: 1024
Output: 10```

Approach:

`        loga b = loge b / loge a`
• Therefore we can calculate log2 N indirectly as:
`        log2 N = loge N / loge 2`

Below is the implementation of the above approach:

Java

 `// Java code to Calculate log base 2 of an integer`   `import` `java.io.*;` `import` `java.lang.*;`   `class` `GFG {`   `    ``// Function to calculate the` `    ``// log base 2 of an integer` `    ``public` `static` `int` `log2(``int` `N)` `    ``{`   `        ``// calculate log2 N indirectly` `        ``// using log() method` `        ``int` `result = (``int``)(Math.log(N) / Math.log(``2``));`   `        ``return` `result;` `    ``}`   `    ``// Driver code` `    ``public` `static` `void` `main(String[] args)` `    ``{`   `        ``int` `N = ``1024``;`   `        ``System.out.println(``"Log "` `+ N + ``" to the base 2 = "` `+ log2(N));` `    ``}` `}`

Output:

`Log 1024 to the base 2 = 10`

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