Thread: stack overflow....

I have run into this peculiar problem of stack overflow and how do i deal with it. The thing is that when i was trying to run the program it was giving that .exe has encountered a problem and will close and all other crap that do you want to tell microsoft about this. But then when i changed to debug mode it gave me the error "Stack Overflow". The program is as follows:

[insert]

Code:

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

#define MAX_WORD_LENGTH 31
#define MAX_WORDS 42000

/* Function prototypes */
int readFile(char* inputFileName, int* wordCount, char array[][MAX_WORD_LENGTH], int flag);
//int qsort(char array[][MAX_WORD_LENGTH], int* wordCount);
int writeToFile(char* outFileName, int wordCount, char array[][MAX_WORD_LENGTH]);
void printTime(time_t  begin);
void usage(char* processName);
// enter any other function prototype you may wish

int main(int argc, char* argv[])
{
        time_t begin;   
		char array[MAX_WORDS][MAX_WORD_LENGTH];
		int wordCount = 0; 
            time(&begin);
		
       	switch (argc)
		{
			case 3:
			readFile(argv[1], &wordCount, array,0);
			writeToFile(argv[2], wordCount, array);
			break;
		case 4:
		{
			if (strcmp(argv[1], "-s") == 0)
			  {
			   readFile(argv[2], &wordCount, array,1);
     		   writeToFile(argv[3], wordCount, array);
			  }
			else if (strcmp(argv[1], "-t") == 0)
			  {
			    readFile(argv[2], &wordCount, array, 1);
			    writeToFile(argv[3], wordCount, array);
			    printTime(begin);
			  }
			else
			  {
			    usage(argv[0]);
			  }
			break;
		}
		case 5:
		default:
	        usage(argv[0]);
	        break;
	}
	return 0;
}

// Define all your functions here
void printTime(time_t  begin)
{
	printf("\nThe time at which it began was %ld", begin); 	
}

void usage(char* processName)
{
  printf("Usage %s [-s] [-t] inputFileName outputFileName\n", processName);
}
			 
int readFile(char* inputFileName, int* wordCount, char array[][MAX_WORD_LENGTH], int flag)
{
	FILE *fp;
	fp = fopen(inputFileName, "r");

	if(fp == NULL)
	{
		printf("\n Unable to open the file. Aborting");
		exit(EXIT_FAILURE);

	}

	if(flag == 0)
	while(fscanf(fp, "%s", array[(*wordCount)++]) > 0);
	else if(flag == 1)
	{
		int i = 0, j= 0, k= 0;
		//sort the elements of the array
		while(fscanf(fp, "\n%s", array[(*wordCount)++]) > 0)
		{
			if(*wordCount> 1)
			{
				for(i =0 ;i<*wordCount; i++)
				{
					j = strcmp(array[i],array[*wordCount]);
					if(j > 0)
					{
						k = *wordCount;
						strcpy(array[k+1], array[k]);
						for(k = *wordCount; k > i; k--)
							strcpy(array[k], array[k-1]);

						break;
					}
				}
			}
		}
	};
	fclose(fp);

	return 0;
}

int writeToFile(char* outFileName, int wordCount, char array[][MAX_WORD_LENGTH])
{
	int i = 0;
	FILE *fp;
	fp = fopen(outFileName, "w");

	if(fp == NULL)
	{
		printf("\n Unable to open the file. Aborting");
		exit(EXIT_FAILURE);
	}
	
	for(i = 0; i< wordCount-1; i++)
	{
		fprintf(fp, "%s\n", array[i]);
	}

	fclose(fp);
	return 0;
}

I have a file dictionary.txt which has some 41000 plus words in it and i want to read it. So how do i overcome this problem of stack overflow...?

I tried making it global but the problem persists though now the error is not stack overflow but its access violation reading some location.

I dont want to make it static because if i make it static i would have to initialize the elements at that point and i would not be able to change it.

char array = malloc(sizeof (char) * (MAX_WORDS * MAX_WORD_LENGTH));

Is this the right way to do malloc of a 2d array.

Okay i figured out the way of doing dynamic memory allocation for a 2d array using
[insert]

Code:

char **array2d;
array2d = malloc(sizeof(char *) * MAX_WORDS);

                  for(i = 0; i< MAX_WORDS;i++){
	  array2d[i] = malloc(sizeof(char) * MAX_WORD_LENGTH);
	  }

but the thing is that the problem still persists. Any ideas on what should be done?

Still unable to make any progress. The same problem is still happening. Could it be a IDE or VS issue that the file size is very large and it is not able to allocate space for this large file size.

Originally Posted by roaan

Still unable to make any progress. The same problem is still happening. Could it be a IDE or VS issue that the file size is very large and it is not able to allocate space for this large file size.

No, I can almost guarantee you that the compiler is not the problem.

Wrap your code in message blocks. For example, put things like "Entering inner loop" and "Exiting innerloop" everywhere you are accessing the array. Once you have an enter and no exit, you can drill down until you hit the problem point in the code.

Part of the problem is going to be right here

Code:

					if(j > 0)
					{
						k = *wordCount;
						strcpy(array[k+1], array[k]);
						for(k = *wordCount; k > i; k--)
							strcpy(array[k], array[k-1]);

						break;
					}

Even though you are shifting everything to the left, you aren't decrementing wordcount. That can lead to issues with grabage being left in the stream, or getting copied to the left. Since C str functions look for the Null character. chances are that it is copying more then it is supposed to (Resulting in an out of bounds error).

This is one of the reasons you should ALWAYS use a function like strncpy that designate buffer size. You are just asking for trouble by letting c go to the null.

Originally Posted by Salem

> char array2d[MAX_WORDS][MAX_WORD_LENGTH];
This is 1.3MB, which is larger than the default 1MB most systems give you for a stack.

You used vart's good advice and got "but its access violation reading some location. " instead.

> while(fscanf(fp, "%s", array2d[(*wordCount)++]) > 0);
So what stops this overflowing the space?

I didnt get by what you mean so what stops this overflowing the space. Isnt fscanf supposed to return -1 when it reaches the end of file. And i have allocated more space than is required for my static array. So it should continue to read into the array.

Vart means that you cannot allocate more than 1MB of memory. It will try to allocate 1.3MB but will fail and give you a stack overflow error. So you don't actually allocate that memory.

Check this out though. Put a breakpoint or a printf("a\n") under

Code:

char array2d[MAX_WORDS][MAX_WORD_LENGTH];

and see if it crashes at that point.

Use your solution to fix this problem even if thare is still a problem. One thing at a time

Code:

char **array2d;
array2d = malloc(sizeof(char *) * MAX_WORDS);
for(i = 0; i< MAX_WORDS; i++){
	  array2d[i] = malloc(sizeof(char) * MAX_WORD_LENGTH);
}

Yes i did that of putting a printf and i understood the fact that i cannot allocate more than 1 Mb of memory. It does not print the contents of printf after the array and it crashes before that saying there is a stack overflow.

I tried using the dynamic memory allocation but there is this error occuring

Unhandled exception at 0x10296551 in classc2.exe: 0xC0000005: Access violation writing location 0x0081a000.

Well, do some debugging. Look where it crashes. Either breakpoints or prinft("OK\n");