[LCP]printf Question

[Andrew Weaver]

In fact, it will print out one more hi than the number of chars you input.

That is, it says Hi, you input AAAA, it will say Hi five times.

Software does exactly what you tell it to do, not always what you meant
but...

What is happening is that getchar returns one char from the stream (stdin).
When you type in a char, you also type in the carriage return don't you? So,
you have two chars in the stream (the char plus the newline). If you want to
see it, add the following line after the getchar() call...

 printf("Input is:%c\n", getchar());

Now, when your prog says "Hi", type in AAA + carriage return. You will see
output like this...

./a.out 
Hi
AAA
Input is:A
Hi
Input is:A
Hi
Input is:A
Hi
Input is:
                           ***** Here is the Carriage Return
Hi

> -----Original Message-----
> From:	sasidhar p [SMTP:psasidhar at hotmail.com]
> Sent:	Thursday, August 30, 2001 10:01 AM
> To:	linuxcprogramming at lists.linux.org.au
> Subject:	[LCP]printf Question
> 
> Hi,
> Can somebody explain me this behaviour, I am all confused....
> main()
> {
>    while(1)
>    {
>       printf("Hi\n");
>       getchar();
>    }
> }
> 
> Out put :
> 
> [psasi at jldev 2]$ ./a.out
> Hi
> a
> Hi
> Hi
> b
> Hi
> Hi
> c
> Hi
> Hi
> d
> Hi
> Hi
> 
> [psasi at jldev 2]$
> 
> I am using gcc on Linux 2.2.14
> why is the "Hi" getting printed twice...
> 
> I tried the following variants, but the o/p pattern is same...
> #include <stdio.h>
> #include <unistd.h>
> 
> main()
> {
>    char buf[]="Hi\n";
>    while (1)
>    {
>       write(1,buf,3);  /* I tried writing to fd 2 also*/
>       getchar();
>    }
> }
> 
> 
> 
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