Fixed XOR

gistfile1.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>


char convert_int_to_hex(int arg)
{
	char result;
	switch(arg)
	{
		case 0: result = '0'; break;
		case 1: result = '1'; break;
		case 2: result = '2'; break;
		case 3: result = '3'; break;
		case 4: result = '4'; break;
		case 5: result = '5'; break;
		case 6: result = '6'; break;
		case 7: result = '7'; break;
		case 8: result = '8'; break;
		case 9: result = '9'; break;
		case 10: result = 'a'; break;
		case 11: result = 'b'; break;
		case 12: result = 'c'; break;
		case 13: result = 'd'; break;
		case 14: result = 'e'; break;
		case 15: result = 'f'; break;
	}
	return result;
}


char convert_bin_to_int(char arg[])
{
	unsigned long arg_len = strlen(arg) - 1;
	int i;
	int j;
	int result = 0;
	char final[512];
	for (i = 0; i <= arg_len; i++)
	{
		if (arg[i] == 49)
		{
			result += pow(2, (arg_len - (i)));
		}
	}
	return convert_int_to_hex(result);
}

void binary_to_hex(char* xor_string)
{
	char four_bit[5];
	char final_result[256];
	unsigned long xor_string_len = strlen(xor_string);
	int i = 0;
	int j = 0;
	int k = 0;
	for (i = 0; i <= xor_string_len; i++) {
		if (j == 4)
		{
			final_result[k] = convert_bin_to_int(four_bit);
			k++;
			j = 0;
		}
		four_bit[j] = xor_string[i];
		j++;
	}
	final_result[xor_string_len] = '\0';
	printf("%s\n", final_result);
}

void binary_xor(char first[], char second[])
{
	unsigned long arg_len = strlen(first) - 1;
	char xor_result[512];
	int i;
	for (i = 0; i <= arg_len; i++)
	{
		if (first[i] != second[i])
		{
			xor_result[i] = '1';
		}
		else 
		{
			xor_result[i] = '0';	
		}
	}
	binary_to_hex(xor_result);
}

char* convert_to_binary(char arg)
{
	char* result;
	switch(arg)
	{
		case '0': result = "0000"; break;
		case '1': result = "0001"; break;
		case '2': result = "0010"; break;
		case '3': result = "0011"; break;
		case '4': result = "0100"; break;
		case '5': result = "0101"; break;
		case '6': result = "0110"; break;
		case '7': result = "0111"; break;
		case '8': result = "1000"; break;
		case '9': result = "1001"; break;
		case 'A': result = "1010"; break;
		case 'B': result = "1011"; break;
		case 'C': result = "1100"; break;
		case 'D': result = "1101"; break;
		case 'E': result = "1110"; break;
		case 'F': result = "1111"; break;
		case 'a': result = "1010"; break;
		case 'b': result = "1011"; break;
		case 'c': result = "1100"; break;
		case 'd': result = "1101"; break;
		case 'e': result = "1110"; break;
		case 'f': result = "1111"; break;
	}
	return result;
}

char* convert_hex(char arg[], char* result)
{
	int i = 0;
	for (i = 0; i < strlen(arg); i++)
	{
		if (i == 0)
		{
			strcpy(result, convert_to_binary(arg[i]));
		}
		else 
		{
			strcat(result, convert_to_binary(arg[i]));
		}
	}
	return result;
}

int main(int argc, char *argv[]) 
{
	char result_one[512];
	char result_two[512];
	char* string_one = convert_hex(argv[1], result_one);
	char* string_two = convert_hex(argv[2], result_two);
	binary_xor(string_one, string_two);
	return 0;
}