Example: C program to Convert Octal Number to Decimal Number

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// C program to Convert Octal Number to Decimal Number
#include <stdio.h>
#include <math.h>

// It's main function of the program
int main() {
    int octal_num;
    int temp_octal_num;
    long long decimal_num;

    printf("Enter Octal Number: ");
    scanf("%d", &temp_octal_num);
    octal_num = temp_octal_num;

    // code block to convert the octal number into decimal number
    int i = 0;
    while(octal_num != 0) {
        decimal_num += (octal_num % 10) * pow(8, i);
        ++i;
        octal_num /= 10;
    }

    // final output of the program
    printf("\n%d Octal = %lld Decimal", temp_octal_num, decimal_num);
    return 0;
}