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In this source code example, we will write a code to convert the Octal to a decimal number in the C programming language.

Convert Octal to Decimal in C

In this C program, we will take input from the User or console and print the result to the output: 

#include <math.h>
#include <stdio.h>

// Converts octal number to decimal
int convertValue(int num, int i) { return num * pow(8, i); }

long long toDecimal(int octal_value)
{
    int decimal_value = 0, i = 0;

    while (octal_value)
    {
        // Extracts right-most digit and then multiplies by 8^i
        decimal_value += convertValue(octal_value % 10, i++);

        // Shift right in base 10
        octal_value /= 10;
    }

    return decimal_value;
}

int main()
{
    printf("Enter octal value: ");

    int octal_value;

    scanf("%d", &octal_value);

    long long result = toDecimal(octal_value);

    printf("%d in decimal is %d\n", octal_value, result);

    return 0;
}

Output:

Enter octal value: 12
12 in decimal is 10

Demo

Related Conversions

1. Convert Binary to Decimal in C
2. Convert Binary to Hexadecimal in C
3. Convert Binary to Octal in C
4. Convert Decimal to Binary in C
5. Convert Decimal to Octal in C
6. Convert Octal to Binary in C
7. Convert Octal to Decimal in C

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