roman_numerals_to_decimal.c File Reference

Conversion of roman numerals to decimal. More...

#include <assert.h>
#include <stdio.h>
#include <string.h>

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Functions
int	symbol (char symbol)
	for assert
int	roman_to_decimal (char input[])
	Converts roman numerals into a decimal number.
static void	test ()
	Self-test implementations.
int	main ()
	Main function.

Detailed Description

Conversion of roman numerals to decimal.

Roman numerals are an ancient Roman numeral system consisting of the symbols I, V, X, L, C, D, and M

Author

Focusucof

Function Documentation

main()

int main

(

void

)

Main function.

Returns

0 on exit

           {
    test();  // run self-test implementations
    return 0;
}

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roman_to_decimal()

int roman_to_decimal

(

char

input[]

)

Converts roman numerals into a decimal number.

Parameters

input

Input roman numeral as a C-string

Returns

The converted number in decimal form

                                   {
    int result = 0; // result in decimal
 
    for(int i = 0; i < strlen(input); i++) {
        if(strlen(input) > i + 1) {
            if(symbol(input[i]) >= symbol(input[i + 1])) {
                result += symbol(input[i]); // add value to sum
            } else {
                result += symbol(input[i + 1]) - symbol(input[i]); // if the current symbol is smaller than the next (ex. IV), subtract it from the next symbol
                i++; // skip over an extra symbol 
            }
        } else {
            result += symbol(input[i]); // add value to sum
        }
    }
    return result;
}

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symbol()

int symbol

(

char

symbol

)

for assert

for IO operations for strlen()

Convert roman numeral symbol to a decimal value helper function

Parameters

symbol

Roman numeral char

Returns

Integer of decimal value for given symbol

                        {
    int value = 0;
    switch(symbol) {
        case 'I':
            value = 1;
            break;
        case 'V':
            value = 5;
            break;
        case 'X':
            value = 10;
            break;
        case 'L':
            value = 50;
            break;
        case 'C':
            value = 100;
            break;
        case 'D':
            value = 500;
            break;
        case 'M':
            value = 1000;
            break;
    }
    return value;    
}

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test()

static void test ( void  )

static

Self-test implementations.

Returns

void

                   {
    // 1st test
    char input[] = "MCMIV";
    int expected = 1904;
    
    int output = roman_to_decimal(input);
 
    printf("TEST 1\n");
    printf("Input: %s\n", input);
    printf("Expected Output: %d\n", expected);
    printf("Output: %d\n", output);
    assert(output == expected);
    printf("== TEST PASSED ==\n\n");
 
    // 2nd test
    char input2[] = "MMMDCCXXIV";
    expected = 3724;
    
    output = roman_to_decimal(input2);
 
    printf("TEST 2\n");
    printf("Input: %s\n", input2);
    printf("Expected Output: %d\n", expected);
    printf("Output: %d\n", output);
    assert(output == expected);
    printf("== TEST PASSED ==\n\n");
 
    // 3rd test
    char input3[] = "III";
    expected = 3;
    
    output = roman_to_decimal(input3);
 
    printf("TEST 3\n");
    printf("Input: %s\n", input3);
    printf("Expected Output: %d\n", expected);
    printf("Output: %d\n", output);
    assert(output == expected);
    printf("== TEST PASSED ==\n\n");
}

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