STRTOK crashes saying access viiolation

[Toufiq S]

heres the piece of code

void main()
{
	char *trial = "((100,1,101),(11,1,12))";
	char *t1;
	int n;
	
for ( t1 = strtok(trial,",");
      t1 != NULL;
      t1 = strtok(NULL, ",") )
{	//n =	atoi("100");// a = strtok(trial," ");
	printf("\n%s",t1);}
	//printf("\n%d",n);
	getch();
}

But it works fine if array is used that is
char trial[] = "((100,1,101),( 11,1,12))";

Can anybody tell me wats the cause of that?

[weaknessforcats]

t1 != NULL;    <-------?
 t1 = strtok(NULL, ",") )
etc...

Have you, by any chance. omitted the if and it's braces?

[Toufiq S]

Hi,

Those three statements are part of the for loop condition split in 3 lines.

Well it works fine just if I change char *t1 to char t1[]..

[Banfa]

strtok writes to the buffer that you provide in order to create the return strings.

When you use char* you are passing a pointer to string constant. Your platform has every write to make string constants constant which would cause an issue when strtok tries to write to it.

However when you use char[] the compiler allocates a buffer for you (on the stack in this case). Since your program owns the buffer and has declared it non-const it is placed in writeable memory and there will be no problem when strtok trys to write to it.