Thread: Run-Time Check Failure #2

The following code runs fine with Pelles C but terminates on MSVC 2010 with an error message
"Run-Time Check Failure #2 - Stack around the variable 'c' was corrupted."

Code:

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

int main()
{
	char s[20][20],*c[20];
	FILE *fp;
	int i,j,words;

	fp=fopen("acc.txt","r");

	words=i=0;
	while(fscanf(fp,"%s",s[i])!=EOF)
	{	words++; i++;	}

	for(i=0;i<words;i++)
		c[i]=s[i];

	for(i=1;i<words;i++)
	{
		for(j=1;j<=words-i;j++)
		{
			if(strcmp(c[j-1],c[j])>0)
			{
				c[20]=c[j-1];
				c[j-1]=c[j];
				c[j]=c[20];
			}
		}
	}

	fclose(fp);
	fp=fopen("acc.txt","w");
	for(i=0;i<words;i++)
		fprintf(fp,"%s ",c[i]);
}

Can someone tell me whats wrong??

The program is a sorting program which reads words from a file and arranges them in alphabetical order..

You never check fp to make sure it opened correctly, so calling fscanf on it if it failed could crash your program. You need to actually return a value from main, usually 0 for success. You have no bounds checking on the data you read in from your file. If you have a word that is over 20 chars, it will overflow s[i]. If you have more than 20 words, you will overflow s in your read loop. Again, when you copy from s[i] to c[i], you don't ensure words < 20. On line 20, you do j <= words, but if words is 20 or more, that's an overflow when you access c[j]. Also, on lines 26 and 28, you use c[20], which is out of bounds. In C, arrays start at 0 and go to size-1, so you only have c[0]...c[19].