BUFSIZ question

[Ash1981]

I was under the impression that BUFSIZ is the size of the buffer, however, if you declare an array and make it's size bufsiz, then use fgets(array, BUFSIZ, stdin); it still seems possible to overflow the buffer. But if BUFSIZ is the size of the buffer, why doesn't this prevent overflowing it?

Also, another small question:

while ((cb=getchar()) != EOF) {

if (cb == '<') {

printf("----------->");

putc(cb);

}

I was trying to make a program to help me out with something in another program I made, hence the code above. It's supposed to wait until the user types "<", then automatically change that to "<------------------>". but it doesn't work, and I was hoping someone might know why.

As always, thanks

--Ash

[OnionKnight]

getchar() waits for the user to press enter, so you would have to type '<' then press enter. If you want something that you described you'd have to use some nonstandard functions like Borland's getch() for Windows or the ncurses library for Linux that would allow you to get characters without waiting for newline.

And doesn't putc() take a file stream as second argument?

[Salem]

> But if BUFSIZ is the size of the buffer, why doesn't this prevent overflowing it?
BUFSIZ is a constant defined in stdio.h, which is vaguely related to the optimal buffer size for your current implementation (but always at least 256). Specifically, it is the size of the buffer which setbuf() uses by default.

char b1[10];
char b2[BUFSIZ];
fgets( b1, sizeof b1, stdin );
fgets( b2, sizeof b2, stdin );
The overflow protection comes from telling fgets the size of the buffer, not the actual size of the buffer.