# C program to convert Decimal to Octal number system

Write a C program to input decimal number from user and convert to octal number system. How to convert from decimal number system to octal number system in C programming. Logic to convert decimal to octal number system in C programming.

Example

Input

`Input decimal: 22`

Output

`Octal number: 26`

## Required knowledge

### Decimal number system

Decimal number system is a base 10 number system. Decimal number system uses 10 symbols to represent all numbers i.e. 0123456789.

### Octal number system

Octal number system is a base 8 number system. Octal number system uses 8 symbols to represent all numbers i.e. 01234567

## Algorithm to convert decimal to octal

```Algorithm Decimal to Octal conversion
begin:
octal ← 0; place ← 1; rem ← 0;
While (decimal > 0) do
begin:
rem ← decimal % 8;
octal ← (rem * place) + octal;
place ← place * 10;
decimal ← decimal / 8;
end;
print('Octal number' octal);
end;```

## Program to convert decimal to octal number system

``````/**
* C program to convert from Decimal to Octal number system
*/

#include <stdio.h>

int main()
{
long long decimal, tempDecimal, octal;
int i, rem, place = 1;

octal = 0;

/* Input decimal number from user */
printf("Enter any decimal number: ");
scanf("%lld", &decimal);

tempDecimal = decimal;

/* Decimal to octal conversion */
while(tempDecimal > 0)
{
rem = tempDecimal % 8;

octal = (rem * place) + octal;

tempDecimal /= 8;

place *= 10;
}

printf("\nDecimal number = %lld\n", decimal);
printf("Octal number = %lld", octal);

return 0;
}``````

Output

```Enter any decimal number: 20
Decimal number = 20
Octal number = 24```

Happy coding 😉 