In this python tutorial, you will learn **how to Convert Octal Number to Decimal** and vice-versa with the built in functions of the python programming language.

## How to Convert Octal Number to Decimal and vice-versa ?

Let’s take a look at the first source code, here the values are given as input by the user in the code, the built in functions carries out the function.

**OCTAL TO DECIMAL**

#Python program to convert Octal Number to a decimal octal_num = input("Enter an octal number :") decimal_value = int(octal_num,8) print("The decimal value of {} is {}".format(octal_num,decimal_value))

**INPUT:**

34

**OUTPUT:**

Enter an octal number : The decimal value of 34 is 28

- Here we give the user the option to enter the values and the input values are scanned using the
`input`

function and are stored in the variable`octal_num`

with the statements/strings`("Enter an octal number :")`

- In the
**STDIN**section of the code editor the input values are entered. - We declare the variable
`decimal_value`

with the function`int(octal_num,8)`

where the`int`

function is used to get the decimal value of the entered integer. - Now, we display the output value using the
`print`

and display the statement/string`("The decimal value of {} is {}".format(octal_num,decimal_value))`

. - In the above statement/string, the variables
`{0}`

and`{1}`

will hold the values of`octal_num`

and`decimal_value`

where the`format`

function helps in variable substitution and data formatting.

Let’s take a look at the second source code, here the values are given as input by the user in the code, the if statement and built in functions carry out the function.

**DECIMAL TO OCTAL**

#Python Program to Convert Decimal Number to Octal decimal_number = int(input("Enter a decimal number :")) octal_number = oct(decimal_number).replace("0o", "") print("\nThe octal value for {0} is {1}".format(decimal_number,octal_number ))

**INPUT:**

100

**OUTPUT:**

Enter a decimal number : The octal value for 100 is 144

- Here we give the user the option to enter the values and the input values are scanned using the
`input`

function and are stored in the variable`decimal_number`

with the statements/strings`("Enter a decimal number :")`

, we use the`int`

function and declare the input value as an integer value. - In the
**STDIN**section of the code editor the input values are entered. - We declare the variable
`octal_number`

with the function`oct(decimal_number)`

along with the`replace`

function which is used to replace the values`("0b","")`

with another value. - Now, we display the output value using the
`print`

and display the statement/string`("\nThe octal value for {0} is {1}".format(decimal_number,octal_number ))`

. - In the above statement/string, the variables
`{0}`

and`{1}`

will hold the values of`decimal_number`

and`octal_number`

where the`format`

function helps in variable substitution and data formatting.

**NOTE:**

- The
**replace()**function is an inbuilt function in the Python programming language that returns a copy of the string where all occurrences of a substring are replaced with another substring. - The
**colon :**at the end of the if and else statement tells Python that the next line of code should only be run if the condition is true. - The
**oct() function**is used to get an octal value of an integer number. - The
**int() function**to get the decimal value of the given integer. - The
**print() function**prints the specified message to the screen, or other standard output device.

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