Thread: how it works..!! is it a flaw in c ??

In future, please post your actual code instead of retyping it (incorrectly with initial capital letters!).

I assume you're wondering why putting a -1 after them doesn't give an error. It's because, although useless, it isn't actually an error. printf and scanf return an int. You are subtracting one from that int, and then throwing the result away.

If you turn up the warning level of your compiler, it should say something about the value not being used.

Originally Posted by Adak

P.S. All tags on the forum must be in all lowercase letters, in order to work.

Actually, the case of the letters doesn't matter. It's the fact that he/she used a backslash (\) instead of a forward slash (/) in the closing tag. It should be:

[code]
int a = 5;
printf(" %d", a) - 1;
...
[/code]

No you don't. GCC does not like exactly what you showed us.

Code:

C:\Users\Josh2>more veera.c
Int a=5;
Printf (" %d",a)-1;
Scanf("%d",&a)-1;
Printf (" %d",a)-1;

C:\Users\Josh2>gcc veera.c
veera.c:1:1: error: unknown type name 'Int'
veera.c:2:9: error: expected declaration specifiers or '...' before string const
ant
veera.c:2:15: error: expected declaration specifiers or '...' before 'a'
veera.c:3:7: error: expected declaration specifiers or '...' before string const
ant
veera.c:3:12: error: expected declaration specifiers or '...' before '&' token
veera.c:4:9: error: expected declaration specifiers or '...' before string const
ant
veera.c:4:15: error: expected declaration specifiers or '...' before 'a'

Which means you typed what you thought was the code from memory.

And, even assuming the best code, turning warnings on produces the following:

Code:

C:\Users\Josh2>more veera.c
#include <stdio.h>
int main()
{
  int a=5;
  printf (" %d",a)-1;
  scanf("%d",&a)-1;
  printf (" %d",a)-1;
  return 0;
}

C:\Users\Josh2>gcc -Wall veera.c
veera.c: In function 'main':
veera.c:5:19: warning: value computed is not used [-Wunused-value]
veera.c:6:17: warning: value computed is not used [-Wunused-value]
veera.c:7:19: warning: value computed is not used [-Wunused-value]

Many compilers, unfortunately, arent configured to be this stringent by default. I suspect vendors do this on purpose in order to make compiler options useful. Learning how to use your IDE or compiler options is important.