7.1 Matching two items against each other
With the if command you can make the script perform a set of commands only when something you specify
is equal or not to something else.
This can be a command that has to be performed, two strings, practically anything.
I don't know how I can explain this very well in words, but it's a simple command once you understand it so I'll
just tell you how it works and give some examples to explain it later on.
The syntax of an if command is if { <action> <compare method> <action>} { <body> }.
The two <action>'s are what the if command must compare to each other.
This can be two strings, a command (don't forgot to enclose
it with brackets like was told in Chapter
3.3) or some text (enclosed in quotes like also told in
Chapter 3.3) or anything
else that can be used to match something against it.
The <compare method> tells the if command how to compare the two actions with each other.
This can be either two things, namely == for 'is equal to' or != for 'is not equal to', when one of the
<action>'s is not a number.
If both <action>'s are a number you can also use the 'is greater than' (>) and the 'is less than' (<) signs
to see whether something is larger than the other (you can for example use as <action>'s two commands that
calculate how many characters there are in a string which both result in a number).
Last but not least, by putting an 'is' (=) sign after the 'is greater than' or 'is less than' sign you can
change 'is greater/less than' into 'is greater/less than OR is the same amount as'.
The <body> is basicly the commands you want the if command to
execute.
The body doesn't have to be on one line, that's why the if
command starts with an open-brace.
You can put a new command on each new line and it'll still
be part of the if command until you close the body
up with a close-brace just like with a procedure.
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