Hey everyone:

Can someone tell me why when I called printf in main I get a blank character. I ran this code in a C interpreter and it works fine, but when I compile with gcc and run it, it doesn't print out the new string. I get a empty string.

I've included the functions that are being called.

Thanks for the help.

int main() {
	char *test = "This is a test 12345";
	char *test2 = splitString(test);
	printf(test2);
}

char* splitString(char* string) {
	char *letterString = NULL;
	char *numberString = NULL;
	char *newString = NULL;
	int stringSize = strlen(string);
	
	newString = malloc(sizeof(char) * stringSize);

	if(newString == NULL) {
		printf("Memory couldnt be allocated");
	}
	
	letterString = findLettersAndPunctuation(string);
	numberString = findNumbers(string);
	strcat(newString, numberString);
	strcat(newString, letterString);
	printf(newString);
	//newString = strcat(numberString,letterString);
	free(letterString);
	free(numberString);
	return newString;
	
}

char* findLettersAndPunctuation(char* string) {
	char *letterString = NULL;
	int stringLength = strlen(string);
	int loopCounter = 0;
	int letterStringCounter = 0;
	
	letterString = malloc(sizeof(char) * (stringLength));
	
	if(letterString == NULL) {
		printf("Memory Could Not be allocated");
		exit(1);
	}
	
	for(loopCounter; loopCounter <= stringLength; loopCounter++) {
		if(isalpha(string[loopCounter]) == 1 || ispunct(string[loopCounter]) == 1
			|| isspace(string[loopCounter]) == 1) {
			letterString[letterStringCounter] = string[loopCounter];
			letterStringCounter++;
		}
	}
	letterString[letterStringCounter] = '\0';
	return letterString;
}

char* findNumbers(char* string) {
	char *numberString = NULL;
	int stringLength = strlen(string);
	int loopCounter = 0;
	int numberStringCounter = 0;
	
	numberString = malloc(sizeof(char) * stringLength);
	
	if(numberString == NULL) {
		printf("Memory Could Not be allocated");
		exit(1);
	}
	
	for(loopCounter; loopCounter <= stringLength; loopCounter++) {
		if(isdigit(string[loopCounter]) == 1) {
			numberString[numberStringCounter] = string[loopCounter];
			numberStringCounter++;
		}
	}
	numberString[numberStringCounter] = ' ';
	numberString[numberStringCounter + 1] = '\0';
	return numberString;
}

Well, its surprising, but here's the solution:
change all your if conditions to this:

if(isalpha(string[loopCounter]) || ispunct(string[loopCounter])	|| isspace(string[loopCounter]) )

i.e. dont check for == 1. The standard for isalpha (and other related functions) says that it returns a value other than zero; doesn't guarantee 1.

Strange, eh?

Edited 5 Years Ago by NP-complete: n/a

The pleasure is all mine...:)
It was quite interesting actually...

Well, There are still a few more gotchas:
1. Do not free() numberString and letterString. You never malloc()'ed them. (try to run it in gcc, and you'll get a seg-fault)
2. Your strcat() wont work because newString is not yet a C-String. So at line 18 add this:

newString[0] = '\0';

3. Also, in your for loops, loop till loopCounter < stringSize (not <=). What you were doing was taking you outside the bounds of your array.
Hope that helps.

Edited 5 Years Ago by NP-complete: n/a

I was freeing those two pointers because they were returned from the two other functions that were called. I did what I needed to do with those two strings and freed them. It didn't cause a seg fault when I ran it.

Thanks

Right, it was giving me a seg-fault when newString[0] = '\0' was not done. After that change, free() is working fine.
My reasoning wsa wrong.
Should have checked...

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