# C++ Program to Convert Octal to Decimal2 min read

In this tutorial, we will write a program to convert octal numbers into decimal numbers in C++. Before that, you must have knowledge of the following topics in C++.

### Octal number

The octal numbers are the numbers with base 8 and use the digits 0 to 7. Example: 8 in decimal is represented as 10 in octal, 25 as 31, and so on.

### Decimal Number

These are the numbers with a base of 10, which ranges from 0 to 9. These numbers are formed with the combination of 0 to 9 digits such as 24, 345, etc.

Let us go through a program for the Octal to Decimal Conversion in C++.

## C++ Program to Convert Octal to Decimal Number

The program takes a user input for an octal number. And then iterate using a while loop. You can also use for loop instead of while loop, the code remains the same. Lastly, display the equivalent decimal value.

One of the libraries math functions (`pow()`) is used. This function returns the value of power calculation maths. It is present in `math.h` header file.

Output:

`Enter the Octal Number: 10Decimal Value: 8`

You can also achieve the octal to decimal conversion using a function in C++. The way to do that is by creating a separate function where you pass the user entered octal value as an argument in a function.

After calculation, the function returns the decimal to the main function where the final result is displayed.

Output:

`Enter an octal number: 10Decimal value: 8`

You may go through the following program for vice-versa:

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