Version number comparator

verscomp.c

/*
 * Uses stdin to evaluate a statement such as "2.5.3" <= 2.4". Returns strings "True" or "False" to terminal
 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

#define DEBUG 0

// helpers
int count_chars(char*, char);
int* split_vers(char*, char*);

int main(int argc, char* argv[])
{
	char* exp; // this is the expression being tested

	// do we have args?
	if (argc == 2)
	{
		exp = malloc(strlen(argv[1] + 1) * sizeof(char));
		strcpy(exp, argv[1]);
	}
	else
	{
		if (isatty(fileno(stdin))) // real terminal?
		{
			printf("Enter expression to test: "); // print data entry prompt if a real term
		}
	
		exp = malloc(256);
		fgets(exp, 256, stdin);
	}

	// split up expression into 3 parts, vers1, logical operator and vers2
	char* sVers1 = strtok(exp, " ");
	char* comp = strtok(NULL, " ");
	char* sVers2 = strtok(NULL, " ");

	// strip the last char if its a newline
	if (sVers2[strlen(sVers2)] == '\n')
	{
		sVers2[strlen(sVers2)-1] = '\0';
	}
	#if DEBUG
		printf("1: '%s'\ncomp: '%s'\n1: '%s'\n", sVers1, comp, sVers2);
	#endif
	
	// count the dots in version1 and 2
	int iVers1count = count_chars(sVers1, '.');
	int iVers2count = count_chars(sVers2, '.');

	// what if no dots are found in the versions?
	if (iVers1count == 0 || iVers2count == 0)
	{
		printf("Error: Must have versions with dot notation.\n");
		exit(255);
	}
	// split the versions into an array using a dot delimiter
	int* aVers1 = split_vers(sVers1, ".");
	int* aVers2 = split_vers(sVers2, ".");

	// which is longest?
	int hiLen = (iVers1count > iVers2count) ? iVers1count + 1: iVers2count + 1;
	int loLen = (iVers1count < iVers2count) ? iVers1count + 1: iVers2count + 1;

	#if DEBUG
		printf("hi: %d\n", loLen);
		printf("lo: %d\n", hiLen);
	#endif

	/* just use ints to store comparisons, enums dont work with switch
		high = 1
		low = -1
		equal = 0
		null = -999
	*/

	// array to record comparisons for indices between versions
	int* comparisons = malloc((hiLen + 1) * sizeof(int*));

	int i; 
	
	// iterate over the longest, storing the comparison result
	for(i=0; i<hiLen; i++)
	{
		if (aVers1[i] > aVers2[i])
		{	
			#if DEBUG
				printf("aVers1[%d] > aVers2[%d]\n", i, i);
			#endif

			comparisons[i] = 1;
		}
		else if ( aVers1[i] < aVers2[i])
		{
			#if DEBUG
				printf("aVers1[%d] < aVers2[%d]\n",i, i);
			#endif

			comparisons[i] =  -1; 
		}
		else
		{
			#if DEBUG
				printf("aVers1[%d] = aVers2[%d]\n", i, i);
			#endif
			
			comparisons[i] = 0;
		}
	}	
	
	free(aVers1);
	free(aVers2);

	int compCount = i; // how many comparisons do we have
	
	#if DEBUG
		printf("%d comparisons stored.\n", compCount);
	#endif	
	
	int finalResult = 0; // assume equal

	// test for full equality
	for (i=0; i<compCount; i++)
	{
		#if DEBUG
			printf("comparisons[%d]: %d\n", i, comparisons[i]);
		#endif
		if (comparisons[i] != 0)
		{
			finalResult = -999;
			#if DEBUG
				printf("comparisons[%d] is not equal.\n", i);
			#endif
			//break;
		}
		else
		{
			#if DEBUG
				printf("comparisons[%d] is equal.\n", i);
			#endif
		}
	}

	if (finalResult == 0)
	{
		goto END;
	}

	// now that we know the versions arent equal...
	for (i=0; i<compCount; i++)
	{
		// is this number equal
		if (comparisons[i] == 0)
		{
			continue; // just move on to next
		}
		
		// if we got here then we have reached the first non-equal comparison
		finalResult = comparisons[i]; // :)
		break;
	}	
	
	free(comparisons);
	free(exp);

	int result = 1; // true or false

	END:
	switch (finalResult)
	{
		case 1:
			result = strstr(comp, ">") ? 0 : 1;
			break;
		case -1:
			result = strstr(comp, "<") ? 0 : 1;
			break;		
		case 0:
			result = strstr(comp, "=") ? 0 : 1;
			break;
	}	
	if (result == 0)
	{
		printf("True\n");
	}
	else
	{
		printf("False\n");
	}

	exit(result);
}

int count_chars(char* s, char c)
{
	int sLen = strlen(s);

	int i;
	int count = 0;
	for(i=0; i<sLen; i++)
	{
		if (s[i] == c)
			count++;
	}
	
	#if DEBUG
		printf("\"%s\" has %d \'%c\'s in it.\n", s, count, c);
	#endif
	
	return count;
}

int* split_vers(char* version, char* delim)
{
	int count = count_chars(version, *delim);
	int* vArray = malloc((count+1) * sizeof(int));
	
	int i = 0; 
	char* vNum;
	
	for (i=0; i<=count; i++)
	{
		if (i == 0) vNum = strtok(version, delim);
		
		if (vNum != NULL)
		{
			vArray[i] = atoi(vNum);
			#if DEBUG
				printf("vArray[%d]: %s\n", i, vNum);
			#endif	
			vNum = strtok(NULL, ".");
		}	
	}

	return vArray;
}