Thread: fseek() changing an unrelated variable?

I'm utterly surprised that IT "WORKS" at all. By all means, this code should crash.

The variable string is a pointer to char that hasn't been given a value, so when you do scanf() you are reading into a undefined memory location - you are just "lucky" enough that it doesn't crash immediately [actualy, if I make a mistake where I use an uninitialized pointer, and it does happen, I prefer it when it crashes immediately, rather than "sort of working but behaving strange", which is the situation you are in].

If you allocate some memory for your "string", you will most likely be able to use it correctly too.

--
Mats

In other words, storing data into a char* isn't going to work. You need to either use an array

Code:

char string[LENGTH];

or dynamically allocate memory for yourself.

Code:

char *string = malloc(length);
/* ... */
free(string);

Note that with this you have to put an upper limit on the number of characters the user can enter. (When calculating sizes, don't forget to take the NULL into account.) You can also resize the allocated memory as required, to allocate just the right amount of memory (or maybe a little more) for your string, but it's a little complicated and I'm not going to explain it right now. (Look into realloc() if you're interested.)

Pedantic note: your FILE* filename variable isn't really a "filename". I usually refer to FILE* pointers as "file pointers" (and UNIX-style int ones as "file descriptors"), while a char* filename like "text.txt" is a "filename".