Golang Example - Convert(cast) Octal to Decimal Number


In this blog post, You will learn two programs in Go language

The first program is to convert Octal to Decimal Number

The second program to convert Decimal to Octal Number.

An Octal number is a number based on the base 8 number system. It contains digits from 0 to 7. In Golang, Octal numbers are always prefixed with zero  Example octal numbers is 0879. Decimal Number are numbers which contain numbers based on base 10.

Example Program to convert Octal to Decimal Number 

We have 2 ways to Convert Octal to Decimal Number in Go language. The following are the ways.

  • Using strconv ParseInt function
  • Custom Function using for loop without inbuilt functions

The below program takes Octal number (prefixed with zero or the normal number for Declaring Octal numbers) and stored in variable octal.

strconv ParseInt function example to cast Octal to Decimal

strconv package provides ParseInt function.To convert Octal number, ParseInt is provided with number and base=8.
Here is an example program for conversion to Decimal Number

package main  
  
import (  
 "fmt"  
 "strconv"  
)  
  
func main() {  
 var octal string  
 fmt.Print("Enter Octal Number:")  
 fmt.Scanln(&octal)  
 output, err := strconv.ParseInt(octal, 8, 64)  
 if err != nil {  
  fmt.Println(err)  
  return  
 }  
  
 fmt.Printf("Output %d", output)  
}  

When the above program is compiled, Output is

Enter Octal Number:045  
Output 37  

Custom Function without Predefined functions 

Created a user-defined function, inside a custom function, used for loop with Modulus, Division operator and Math pow function.
Here is an example program

package main  
  
import (  
 "fmt"  
 "math"  
)  
  
func convertOctaToDecimal(number int) int {  
 decimal := 0  
 counter := 0.0  
 remainder := 0  
  
 for number != 0 {  
  remainder = number % 10  
  decimal += remainder * int(math.Pow(8.0, counter))  
  number = number / 10  
  counter++  
 }  
 return decimal  
}  
  
func main() {  
 var octal int  
 fmt.Print("Enter Octal Number:")  
 fmt.Scanln(&octal)  
  
 fmt.Printf("Output %d", convertOctaToDecimal(octal))  
  
}  

Output is

Enter Octal Number:25  
Output 21  

Example Program to convert Decimal to Octal Number 

We have 2 ways to convert Decimal to Octal number in Golang.
Below are two ways

  • using strconv FormatInt function 
  • Without Inbuilt Function 

The below program takes decimal input number from keyboard console, stores it in variable decimal.

strconv FormatInt function example to convert Decimal to Octal 

Inbuilt Standard package strconv provides FormatInt function used to convert Decimal to Octal number.
Here is an example program for Casting Decimal to Octal

package main  
  
import (  
 "fmt"  
 "math"  
 "strconv"  
)  
func main() {  
 var decimal int64  
 fmt.Print("Enter Decimal Number:")  
 fmt.Scanln(&decimal)  
 output := strconv.FormatInt(decimal, 8)  
 fmt.Print("Output ", output)  
  
}  

The output of the compiled program is

Enter Decimal Number:124  
Output 174  

Custom function without inbuilt functionality 

The following program uses Golang features For loop, Modulus and division operators.
Here is an example program to do the conversion.

package main  
  
import (  
 "fmt"  
)  
  
func convertDecimalToOctal(number int) int {  
 octal := 0  
 counter := 1  
 remainder := 0  
 for number != 0 {  
  remainder = number % 8  
  number = number / 8  
  octal += remainder * counter  
  counter *= 10  
 }  
 return octal  
}  
  
func main() {  
 var decimal int  
 fmt.Print("Enter Decimal Number:")  
 fmt.Scanln(&decimal)  
 fmt.Print("Output ", convertDecimalToOctal(decimal))  
  
}  

Output is

Enter Decimal Number:145  
Output 221  

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