## C, conversion, octal_to_hexadecimal.c

``````/**
* @file
* @brief Octal to hexadecimal conversion by scanning user input
* @details
* The octalToHexadecimal function take the octal number as long
* return a string hexadecimal value after conversion
* @author [Rachit Bhalla](https://github.com/rachitbhalla)
*/
#include <assert.h> // for assert
#include <math.h> // for pow function
#include <stdio.h> // for scanf and printf functions
#include <stdlib.h> // for malloc and free functions
#include <string.h> // for strcmp function

/**
* @brief Convert octal number to decimal number
* @param octalValue is the octal number that needs to be converted
* @returns a decimal number after conversion
*/
long octalToDecimal(long octalValue){
long decimalValue = 0;
int i = 0;
while (octalValue) {
// Extracts right-most digit, multiplies it with 8^i, and increment i by 1
decimalValue += (long)(octalValue % 10) * pow(8, i++);
// Shift right in base 10
octalValue /= 10;
}
return decimalValue;
}

/**
* @brief Convert octal number to hexadecimal number
* dynamically allocated memory needs to be freed by the calling the function free
* @param octalValue is the octal number that needs to be converted
* @returns a hexadecimal value as a string after conversion
*/
char *hexadecimalValue = malloc(256 * sizeof(char));
}

/**
* @brief Test function
* @returns void
*/
static void test() {
/* test that hexadecimal value of octal number 213 is 8B */
assert(strcmp(octalToHexadecimal(213), "8B") == 0);

/* test that hexadecimal value of octal number 174 is 7C */
assert(strcmp(octalToHexadecimal(174), "7C") == 0);
}

/**
* @brief Main function
* @returns 0 on exit
*/
int main()
{
// execute the tests
test();

// get the value of octal number as input
int octalValue;
printf("Enter an octal number: ");
scanf("%d", &octalValue);

// call the function octalToHexadecimal and print the hexadecimal value