{"id":633,"date":"2024-10-10T10:52:05","date_gmt":"2024-10-10T05:22:05","guid":{"rendered":"https:\/\/codexplained.in\/?p=633"},"modified":"2025-11-24T16:01:51","modified_gmt":"2025-11-24T10:31:51","slug":"converting-hexadecimal-to-decimal","status":"publish","type":"post","link":"https:\/\/codexplained.in\/?p=633","title":{"rendered":"Converting Hexadecimal to Decimal."},"content":{"rendered":"
\n#include <stdio.h>\n#include <string.h>\n#include <math.h>\n\n\/\/ Function to convert a hexadecimal character to its decimal value\nint hexCharToDecimal(char hexChar) {\n    if (hexChar >= '0' && hexChar <= '9') {\n        return hexChar - '0';  \/\/ For characters '0' to '9'\n    } else if (hexChar >= 'A' && hexChar <= 'F') {\n        return hexChar - 'A' + 10;  \/\/ For characters 'A' to 'F'\n    } else if (hexChar >= 'a' && hexChar <= 'f') {\n        return hexChar - 'a' + 10;  \/\/ For lowercase 'a' to 'f'\n    }\n    return -1;  \/\/ Invalid character\n}\n\n\/\/ Function to convert Hexadecimal to Decimal\nint hexadecimalToDecimal(char hex[]) {\n    int decimalNumber = 0;\n    int length = strlen(hex);  \/\/ Find the length of the hex string\n\n    for (int i = 0; i < length; i++) {\n        int value = hexCharToDecimal(hex[i]);  \/\/ Get decimal value of each hex character\n        decimalNumber += value * pow(16, length - i - 1);  \/\/ Convert to decimal\n    }\n\n    return decimalNumber;\n}\n\nint main() {\n    char hex[20];\n\n    \/\/ Input a hexadecimal number from the user\n    printf("Enter a hexadecimal number: ");\n    scanf("%s", hex);\n\n    \/\/ Convert the hexadecimal number to decimal and display the result\n    int decimalNumber = hexadecimalToDecimal(hex);\n    printf("Decimal equivalent: %d\\n", decimalNumber);\n\n    return 0;\n}\n\n<\/pre><\/div>\n\n\n
Explanation:<\/h2>\n\n\n\n
Header Files<\/strong>:<\/p>\n\n\n\n
    \n
  • #include <stdio.h><\/code>: This is for standard input\/output functions like printf()<\/code> and scanf()<\/code>.<\/li>\n\n\n\n
  • #include <string.h><\/code>: This is for functions that deal with strings, like strlen()<\/code>, which calculates the length of the hexadecimal input.<\/li>\n\n\n\n
  • #include <math.h><\/code>: This is for the pow()<\/code> function, which is used to calculate powers of 16.<\/li>\n<\/ul>\n\n\n\n
    hexCharToDecimal Function<\/strong>:<\/p>\n\n\n\n
      \n
    • This function takes a single hexadecimal character (e.g., ‘A’, ‘5’) and converts it into its decimal equivalent.<\/li>\n\n\n\n
    • If the character is a number (0-9<\/code>), it converts it by subtracting the ASCII value of '0'<\/code>.<\/li>\n\n\n\n
    • If the character is a letter (A-F<\/code> or a-f<\/code>), it converts it by subtracting the ASCII value of 'A'<\/code> or 'a'<\/code>, then adding 10<\/code>.<\/li>\n<\/ul>\n\n\n\n
      hexadecimalToDecimal Function<\/strong>:<\/p>\n\n\n\n
        \n
      • This function takes the entire hexadecimal string as input (e.g., “1A3”) and converts it to decimal.<\/li>\n\n\n\n
      • It starts by calculating the length of the input string.<\/li>\n\n\n\n
      • It loops through each character of the string, converts each hex digit to its decimal equivalent using hexCharToDecimal()<\/code>, and calculates the decimal number by multiplying each digit with the appropriate power of 16.<\/li>\n<\/ul>\n\n\n\n
        main Function<\/strong>:<\/p>\n\n\n\n
          \n
        • The main function takes a hexadecimal number as input from the user (as a string), calls the hexadecimalToDecimal()<\/code> function to perform the conversion, and prints the result.<\/li>\n<\/ul>\n\n\n\n
          Output:<\/h2>\n\n\n\n
          Input<\/strong>: 1A3<\/code><\/p>\n\n\n\n
          Output<\/strong>:<\/p>\n\n\n\n
          Enter a hexadecimal number: 1A3
          Decimal equivalent: 419
          <\/code><\/pre>\n\n\n\n
          Input<\/strong>: FF<\/code><\/p>\n\n\n\n
          Output<\/strong>:<\/p>\n\n\n\n
          Enter a hexadecimal number: FF
          Decimal equivalent: 255
          <\/code><\/pre>\n