For Loop
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m (1 revision) |
Latest revision as of 12:38, 14 June 2015
Contents |
For As
Description
Loop based on an expression.
for ( <expression1> ; <expression2> ; <expression3> )
{
statements
...
}
Parameters
expression1
An expression to execute before starting the loop.
You can add multiple expressions by separating them with a ,
expression2
An expression to evaulate and check if its TRUE.
If it is not TRUE the loop will end (Or not even begin).
You can add multiple expressions by separating them with a ,
If you have multiple expressions to be checked here it will require ALL of them to be true
expression3
An expression to execute after each cycle of the loop.
Usually $i++ or $i += something
You can add multiple expressions by separating them with a ,
Remarks
For statements may be nested.
The expression2 can contain the boolean operators of &&, ||, ! as well as the logical operators <, <=, >, >=, ==, !=, <>, eq, eqi, neq and neqi as needed grouped with parentheses as needed.
Example
Count up to from 1 to 10
for ( $i = 1; $i <= 10; $i++ ) { println( "Value is $i" ); }
Count down to from 10 to 1
for ( $i = 10; $i > 0; $i-- ) { println( "Value is $i" ); }
Count up to from 2 to 20 counting in 2s
for ( $i = 2; $i <= 20; $i += 2 ) { println( "Value is $i" ); }
Of course can check $i a few times
for ( $i = 0; $i >= 0 && $i < 30; $i++ ) { println( "Value is $i" ); }
Using multiple expressions
for ( $i = 0, $j = 3; $i < 10; $i++, $j++ ) { println( "Value is $i -- $j" ); }
Using multiple expressions with multiple comparison it will print the same as the one above since it will only continue looping if *all* the comparisons are *true*
# basically this is equal to using # $i < 10 && $j < 20 for ( $i = 0, $j = 3; $i < 10, $j < 20; $i++, $j++ ) { println( "Value is $i -- $j" ); }
Print all array elements Method 1
$arr = array( "One", "Two", "Three", "Four", "Five" ); for ( $i = 0; $i < UBound($arr); $i++ ) { $item = $arr[$i]; println( "Value is " . $item ); }
Print all array elements Method 2
$arr = array( "One", "Two", "Three", "Four", "Five" ); for ( $i = 0; $i < UBound($arr); $i++ ) { println( "Value is $arr[$i]" ); }
A perl style number to number for
for( 0 .. 10 ) { println("Value $_"); // Yes the $_ gets set just like in Perl } // or for( 0 .. 10 as $i ) { println("Value $i"); // Yes the $_ gets set just like in Perl } // You can join the numbers together at the .. // A Reverse style my $x = 5; println("Hello $_") for(3..$x);
Another perl style but this time using variables
$a = 1; $b = 30; for( $a..$b ) { println("Value $_"); // Yes the $_ gets set just like in Perl } // or for( $a..$b as $i ) { println("Value $i"); // Yes the $_ gets set just like in Perl } // You can join numbers together at the .. for( 0..10 ) { println("Value $_"); // Yes the $_ gets set just like in Perl } // or for( 0..10 as $i ) { println("Value $i"); // Yes the $_ gets set just like in Perl } // You can also count down // You can join numbers together at the .. for( 10..0 ) { println("Value $_"); // Yes the $_ gets set just like in Perl } // or for( 10..0 as $i ) { println("Value $i"); // Yes the $_ gets set just like in Perl } // A Reverse style println("Hello $k") for(3..$x as $k);
Another Perl style but this time using Hex numbers
for( 0x1E..0x2F ) { println("Value $_"); } // or for( 0x00..0x1B as $i ) { println("Value $i"); } // Countdown for( 0x2F..0x1E ) { println("Value $_"); } // or for( 0x1B..0x00 as $i ) { println("Value $i"); }
Another Perl style but this time using a Step counting up
// Digits for( 10..20 by 2 ) { println("Value $_"); } // Hex for( 0x00..0x1B by 0x02 as $i ) { println("Value $i"); } // Var my $first = 15; my $second = 21; for( $first..$second by 2 as $i ) { println("Value $i"); }
Another Perl style but this time using a Step counting down
// Digits for( 20..10 by 2 ) { println("Value $_"); } // Hex for( 0x1B..0x00 by 0x02 as $i ) { println("Value $i"); } // Var my $first = 21; my $second = 15; for( $first..$second by 2 as $i ) { println("Value $i"); }
