User Manual

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271
CATC MERLINS WAND 1.22 APPENDIX D
User’s Manual CATC Scripting Language
2, 3, 4,
for Statements
A for statement takes the form
for (<expression1>; <expression2>;
<expression3>) <statement>
The first expression initializes, or sets, the starting value for x. It is executed
one time, before the loop begins. The second expression is a conditional
expression. It determines whether the loop will continue -- if it evaluates
true, the function keeps executing and proceeds to the statement; if it
evaluates false, the loop ends. The third expression is executed after every
iteration of the statement.
The example
for ( x = 2; x < 5; x = x + 1 ) Trace ( x, "\n" );
would output
2
3
4
The example above works out like this: the expression x = 2 is executed.
The value of x is passed to x < 5, resulting in 2 < 5. This evaluates to
true, so the statement Trace (x, "\n" ) is performed, causing 2 and
a new line to print. Next, the third expression is executed, and the value of
x is increased to
3. Now, x < 5 is executed again, and is again true, so the
Trace statement is executed, causing 3 and a new line to print. The third
expression increases the value of x to 4; 4 < 5 is true, so 4 and a new line
are printed by the Trace statement. Next, the value of x increases to 5.
5<5 is not true, so the loop ends.