unusual code.
Hi all,
This code runs in gcc 3.4.2 and prints "Hi there!".
Can anybody plz explain this to me?Code:#include <stdio.h> void print() { printf("Hi there!"); } int main() { int i; printf; "Hello", i; getchar; print(); getchar(); return 0; }
Thanks n regards,
Arun
Explain what?
> printf; "Hello", i;
> getchar;
These are all expressions - they don't evaluate to a function call (you need some () to make that happen), and the result isn't assigned anywhere.
You can just delete the first two lines and nothing will change.
I mean, if you had a function pointer, you might do this
int (*fn)(void) = getchar;
But since there is no left hand side of the expression, nothing happens.
I get
gcc -W -Wall -ansi -pedantic -O2 foo.c
foo.c: In function `main':
foo.c:10: warning: left-hand operand of comma expression has no effect
foo.c:10: warning: statement with no effect
foo.c:10: warning: statement with no effect
foo.c:11: warning: statement with no effect
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Hi!
That's what I wanted to know. What's there in this "()"?
If I comment out the declaration of "i" at the 3rd line in "main()" I get the error " 'i' undeclared ". But there is no such error for "printf" or "getchar".
How are "printf" and "getchar" exactly interpreted?
Thanks,
Arun
Well they're just symbols declared in stdio.h.
Normally, they're functions - when you have () following them - regard () as the function call operator.
But without (), the symbol names are just 'pointer to function', and can be assigned like any other variable.
Or in this case, not assigned at all, and hence the "statement has no effect"
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Hi!
Thanks a lot for reminding me!
I really missed the point that function names are nothing but pointers.
Regards,
Arun
