while loop question

[rzed]

I coded a while loop this way:
while( fgets( buff, MAXBUFF, ifp ) != NULL && rtype == 0 )
....

with the effect that buff contained every other line in the file (that is, the first, third, fifth, etc.).

Coding it this way:
while( rtype == 0 && fgets( buff, MAXBUFF, ifp ) != NULL )
....

put every line in the file in buff. 'rtype' was set to zero before the loop in each case, and within the loop it might or might not be altered, but that logic did not change.

What's going on here? Why would I get different results?

 

[rzed]

I coded a while loop this way:

while( fgets( buff, MAXBUFF, ifp ) != NULL && rtype == 0 )

...



with the effect that buff contained every other line in the file (that is, the first, third, fifth, etc.).



Coding it this way:

while( rtype == 0 && fgets( buff, MAXBUFF, ifp ) != NULL )

...



put every line in the file in buff. 'rtype' was set to zero before the loop in each case, and within the loop it might or might not be altered, but that logic did not change.



What's going on here? Why would I get different results?

Never mind. Silly me. Changing the order shortcuts the condition evaluation, of course. Slap! Slap!

 

[glen herrmannsfeldt]

(snip)
(snip)
Never mind. Silly me. Changing the order shortcuts the condition
evaluation, of course. Slap! Slap!

I presume there is a loop that you didn't show.

Also, you may or may not find a do{}while loop to be useful.

-- glen