Please explain this PHP syntax

Question

I've looked up the functions in the manual, but I still don't get this. According to the person who wrote the code, if the User enters "y" then the function (not shown here) will execute. However, because of the !, it looks to me like the function (not shown here) will execute if the user enters something other than "y".

Please explain (I"m a relative newbie so as much detail as possible would be helpful). Thanks

if(!strncasecmp(trim(fgets(STDIN)),'y',1))

Is this in the context of a command line application?

Pekka
– Pekka

2011-06-03 09:05:16 +00:00
Commented Jun 3, 2011 at 9:05 — Pekka
– Pekka, Commented Jun 3, 2011 at 9:05
yes, the script is creating a shell tool

Leahcim
– Leahcim

2011-06-03 09:07:19 +00:00
Commented Jun 3, 2011 at 9:07 — Leahcim
– Leahcim, Commented Jun 3, 2011 at 9:07

codaddict · Accepted Answer · 2011-06-03 09:11:20Z

10

fgets(STDIN) - reads a string from standard input(keyboard in your case).

trim - removes any spaces surrounding the user input. So if the user enters ' y' or a 'y ', it'll be converted to 'y'

strncasecmp - The user might enter either uppercase Y or lowercase y, this function helps you to compare case insensitive way. Also this function returns 0 if the comparison is successful and then you use the ! (not operator) which changes the 0 to a 1 so that the if test passes.

You could re-write it as:

if(strncasecmp(trim(fgets(STDIN)),'y',1) == 0)

edited Jun 3, 2011 at 9:11

answered Jun 3, 2011 at 9:08

codaddict

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csl · Accepted Answer · 2011-06-03 09:05:38Z

4

The function strncasecmp returns 0 if there is no difference between the strings compared, hence the ! to check if they're equal.

answered Jun 3, 2011 at 9:05

csl

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1 Comment

Matt Gibson Over a year ago

Yes. Many string comparison functions in a variety of languages/libraries return like this, for sorting purposes -- negative value if the string is "less" than the comparison string, positive value if it's "more" than the comparison string, zero if equal.

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