[Kestral]

Hi All,

Still working on Dave Mark's Programming C For the Macintosh book. I typed in the program exactly as it looked in the book, but unlike the first program, this program will not run, could someone please tell me what's wrong with it?

int main ( void )
{
int index, num, sum;
sum =0;

for ( index=1; index<=5; index++ )

{
printf ( "Enter number %d --->", index );
scanf ( "%d", %num );
sum=sum+num;
}

printf ( "The sum of these numbers is %d.",sum );

return 0;
}

[lenz]

what error do you get?

[Synaptic]

It's a really long time since I did any C programming but first guess is that your second argument to scanf is wrong. Try replacing it with &num (that's ampersand followed by num). scanf takes a pointer to constant char. Hopefully when you tried to compile it your compiler spat out an error message relating to this line.

[kido]

This works for me in Project Builder as a Standard Tool. I made two changes - I added a fflush (stdout); to make the printf line show up, and the second argument to scanf should be &num, not %num.

#include <stdio.h>

int main ( void ) {

int index, num, sum;
sum = 0;


for ( index=1; index<=5; index++ ) {
printf ( "Enter number %d ---> ", index );
fflush (stdout);
scanf ( "%d", &num );
sum=sum+num;
}

printf ( "The sum of these numbers is %d.",sum );
return 0;
}

[ShortcutToMoncton]

Yup, you need an anpersand (sp?) to scan, not a percent. I'm not sure what the fflush adds, though. It should work without it, I think.

greg

[chadseld]

Yeah, there is a bug in OSX that doesn't flush the cout/fprint buffer like one would expect. Put int an endln and it will show up.

[Kestral]

Thanks for the tips y'all - yup, turns out that I had a typo there which caused the compile error. Turns out I had "%num" instead of "&num". Still getting the hang of learning C but geez, I better start typing these programs right!! lol

BTW, the program ran fine without the "fflush (stdout);".

[Wixar]

I'm not aware of any bug in OS X regarding flushing stdout for C programs.

There are three cases when a C program is required to flush stdout that I know of:

1) A newline character \n is output to it
2) fflush(stdout) is called
3) The program terminates

So yes, the fflush(stdout) should be there; otherwise, the program is not strictly portable and may not print th line "Enter number %d --->" until after it finishes.

-Peter