if statement

malikah · 07-10-2008, 03:47 PM

Is there a mistake in the following code?

printf "${wrdCpy[$a]}" ##Prints the letter "A"
printf "$guess" ##Prints the letter "A"

if [ "$guess" == "${wrdCpy[$a]}" ]
##Tries to tell me that "A" is not equal to "A"..

ntubski · 07-10-2008, 09:59 PM

Works for me, note that if you don't put a space around the brackets or == it won't work right.

Code:

~/tmp$ wrdCpy=(A B C)
~/tmp$ guess=A
~/tmp$ a=0
~/tmp$ printf "${wrdCpy[$a]}" ##Prints the letter "A"
A~/tmp$ printf "$guess" ##Prints the letter "A"
A~/tmp$ if [ "$guess" == "${wrdCpy[$a]}" ] ; then echo "A equals A" ; else echo "A doesn't equal A" ; fi
A equals A

Also I think it should be [ "$guess" = "${wrdCpy[$a]}" ], although it seems to work fine with ==.

Mr. C. · 07-10-2008, 10:06 PM

Actually, I just learned something new today regarding "=" and "==".

Bash allows either, with the single = being POSIX compliant, but the preferred being double equals.
man test shows only a single = as being correct.

So, the behavior depends on the shell and which test is used (built-in v. /usr/bin/test command, which is likely rarely used today).