# C Program To Convert Octal To Decimal

In this post, we will learn how to convert octal to decimal using C Programming language.

We will take an octal number as an input and convert it into a decimal number using a user-defined function.

So, without further ado, letâ€™s begin this tutorial.

## C Program To Convert Octal To Decimal

```// C Program To Convert Octal To Decimal
#include <stdio.h>
#include <math.h>

long octaltodecimal(int num){
int temp = 0, decimal = 0;

while (num != 0){
decimal = decimal + (num % 10) * pow(8, temp);
temp++;
num = num / 10;
}
return decimal;
}

int main(){
int num;

printf("Enter an octal number: ");
scanf("%d", &num);

printf("Equivalent decimal number after conversion is: %d", octaltodecimal(num));
return 0;
}
```

Output

``````Enter an octal number: 64
Equivalent decimal number after conversion is: 52
``````

## How Does This Program Work ?

``````long octaltodecimal(int num){
int temp = 0, decimal = 0;

while (num != 0){
decimal = decimal + (num % 10) * pow(8, temp);
temp++;
num = num / 10;
}
return decimal;
}
``````

In this program, we have defined a custom function named octaltodecimal which will convert the octal number into a decimal number.

``````    printf("Equivalent decimal number after conversion is: %d", octaltodecimal(num));
``````

We call this custom function in the main() function which will ultimately print the value obtained after conversion.

## Conclusion

I hope after going through this post, you understand how to convert octal to decimal number using C Programming language.

If you have any doubt regarding the program, feel free to contact us in the comment section. We will be delighted to help you.