Merge pull request #677 from rachitbhalla/master

Implemented octal to hexadecimal conversion

DIRECTORY.md

@@ -21,6 +21,7 @@
   * [Int To String](https://github.com/TheAlgorithms/C/blob/master/conversions/int_to_string.c)
   * [Octal To Binary](https://github.com/TheAlgorithms/C/blob/master/conversions/octal_to_binary.c)
   * [Octal To Decimal](https://github.com/TheAlgorithms/C/blob/master/conversions/octal_to_decimal.c)
+  * [Octal To Hexadecimal](https://github.com/TheAlgorithms/C/blob/master/conversions/octal_to_hexadecimal.c)
   * [To Decimal](https://github.com/TheAlgorithms/C/blob/master/conversions/to_decimal.c)
 
 ## Data Structures

conversions/octal_to_hexadecimal.c

@@ -0,0 +1,79 @@
+/**
+ * @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 *octalToHexadecimal(long octalValue){
+    char *hexadecimalValue = malloc(256 * sizeof(char));
+    sprintf(hexadecimalValue, "%lX", octalToDecimal(octalValue));
+    return hexadecimalValue;
+}
+
+/**
+ * @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
+    char *hexadecimalValue = octalToHexadecimal(octalValue);
+    printf("Equivalent hexadecimal number is: %s", hexadecimalValue);
+
+    // free the memory allocated dynamically in function octalToHexadecimal
+    free(hexadecimalValue);
+
+    // return 0 and exit
+    return 0;
+}