{"id":599,"date":"2024-10-10T10:52:31","date_gmt":"2024-10-10T05:22:31","guid":{"rendered":"https:\/\/codexplained.in\/?p=599"},"modified":"2025-11-24T16:01:01","modified_gmt":"2025-11-24T10:31:01","slug":"converting-octal-to-decimal","status":"publish","type":"post","link":"https:\/\/codexplained.in\/?p=599","title":{"rendered":"Converting octal to decimal"},"content":{"rendered":"
\n#include <stdio.h>\n#include <string.h>\n#include <math.h>\n\n\/\/ Function to convert octal to decimal\nint octalToDecimal(const char *octal) {\n    int decimal = 0;  \/\/ Variable to store the decimal value\n    int length = strlen(octal);  \/\/ Get the length of the octal string\n\n    \/\/ Loop through each character in the octal string\n    for (int i = 0; i < length; i++) {\n        \/\/ Convert the character to an integer\n        int digit = octal[length - 1 - i] - '0';  \/\/ Extract digit from right to left\n        decimal += digit * pow(8, i);  \/\/ Add to decimal value\n    }\n\n    return decimal;  \/\/ Return the computed decimal value\n}\n\nint main() {\n    char octal[20];  \/\/ Array to hold octal input\n\n    \/\/ Get user input\n    printf("Enter an octal number: ");\n    scanf("%19s", octal);  \/\/ Read the octal input\n\n    \/\/ Call the conversion function\n    int decimal = octalToDecimal(octal);\n    printf("Decimal equivalent: %d\\n", decimal);  \/\/ Print the result\n\n    return 0;  \/\/ Indicate successful completion\n}\n\n<\/pre><\/div>\n\n\n
Explanation:<\/h2>\n\n\n\n
Explanation:<\/h3>\n\n\n\n
    \n
  1. Header Files<\/strong>:\n
      \n
    • #include <stdio.h><\/code>: This is for standard input and output functions like printf()<\/code> and scanf()<\/code>.<\/li>\n\n\n\n
    • #include <math.h><\/code>: This is used to calculate powers (pow()<\/code>) in the program, which is necessary to convert octal digits to decimal.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
    • octalToDecimal Function<\/strong>:\n
        \n
      • This function takes an integer as input, which represents the octal number.<\/li>\n\n\n\n
      • It initializes two variables: decimalNumber<\/code> to store the result and i<\/code> to keep track of the power of 8.<\/li>\n\n\n\n
      • The loop runs while octalNumber<\/code> is not zero.<\/li>\n\n\n\n
      • Inside the loop:\n
          \n
        • remainder = octalNumber % 10<\/code>: This extracts the last digit of the octal number.<\/li>\n\n\n\n
        • decimalNumber += remainder * pow(8, i)<\/code>: The digit is multiplied by 8^i<\/code> and added to the decimal number.<\/li>\n\n\n\n
        • octalNumber \/= 10<\/code>: The last digit is removed.<\/li>\n\n\n\n
        • i++<\/code>: This increments the power of 8 for the next digit.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n\n\n\n
        • main Function<\/strong>:\n
            \n
          • This is where the execution starts. It first asks the user to input an octal number.<\/li>\n\n\n\n
          • Then it calls the octalToDecimal<\/code> function to perform the conversion and prints the result.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n
            Output:<\/h2>\n\n\n\n
            Enter an octal number: 157\nDecimal equivalent: 111<\/code><\/pre>\n\n\n\n
            How It Works:<\/h3>\n\n\n\n
              \n
            • When you input 157<\/code> (octal), the program treats it as:\n
                \n
              • 7 * 8^0 = 7<\/code><\/li>\n\n\n\n
              • 5 * 8^1 = 40<\/code><\/li>\n\n\n\n
              • 1 * 8^2 = 64<\/code><\/li>\n\n\n\n
              • Total = 7 + 40 + 64 = 111<\/code> in decimal.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n