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Lou Montana (talk | contribs) m (Text replacement - "\[\[Category:[ _]?Scripting[ _]Commands[ _]Arma[ _]2(\|.*)\]\]" to "{{GameCategory|arma2|Scripting Commands}}") |
Lou Montana (talk | contribs) m (Text replacement - "_{10,} " to "") |
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{{Command|Comments= | {{Command|Comments= | ||
| arma1 |Game name= | | arma1 |Game name= | ||
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|1.00|Game version= | |1.00|Game version= | ||
| This operator creates a [[For Type]] which is used in the for-constructs. | | This operator creates a [[For Type]] which is used in the for-constructs. | ||
{{Important|Alternative syntax {{Inline code|[[for]] ''array'' [[do]] ''code''}} is [[Code_Optimisation#for|slower]] than the alternative because the condition is checked every iteration.}} |Description= | {{Important|Alternative syntax {{Inline code|[[for]] ''array'' [[do]] ''code''}} is [[Code_Optimisation#for|slower]] than the alternative because the condition is checked every iteration.}} |Description= | ||
| [[for]] arguments |Syntax= | | [[for]] arguments |Syntax= | ||
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| [[For Type]] |Return value= | | [[For Type]] |Return value= | ||
|s2= [[for]] [init, condition, codeToExecute] |Syntax 2= | |s2= [[for]] [init, condition, codeToExecute] |Syntax 2= | ||
| Line 29: | Line 25: | ||
|r2= [[For Type]] |Return value 2= | |r2= [[For Type]] |Return value 2= | ||
|x1= <code>{{cc|will output 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 (the to value being inclusive)}} | |x1= <code>{{cc|will output 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 (the to value being inclusive)}} | ||
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[[for]] [{[[private]] _i = 0}, {_i < 5}, {_i = _i + 1}] [[do]] {}; | [[for]] [{[[private]] _i = 0}, {_i < 5}, {_i = _i + 1}] [[do]] {}; | ||
[[hint]] [[str]] _i; {{cc|100}}</code> |Example 4= | [[hint]] [[str]] _i; {{cc|100}}</code> |Example 4= | ||
| [[Control Structures]], [[while]], [[do]] |See also= | | [[Control Structures]], [[while]], [[do]] |See also= | ||
Revision as of 01:15, 17 January 2021
Description
- Description:
- This operator creates a For Type which is used in the for-constructs.
- Groups:
- Program Flow
Syntax
- Syntax:
- for arguments
- Parameters:
- arguments: String - declares the index variable name like "_myVar". from and to are required, step is optional.
- Return Value:
- For Type
Alternative Syntax
- Syntax:
- for [init, condition, codeToExecute]
- Parameters:
- init: Code - loop variable definition
- condition: Code - called code returns false, leave the for-loop
- codeToExecute: Code - code to be run on each loop
- Return Value:
- For Type
Examples
- Example 1:
// will output 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 (the to value being inclusive) for "_i" from 1 to 10 do { systemChat str _i; };- Example 2:
for "_i" from 9 to 1 step -2 do { systemChat str _i; };- Example 3:
for [{ _i = 0 }, { _i < 10 }, { _i = _i + 1 }] do { systemChat str _i };- Example 4:
// BAD CODE _i = 100; for [{_i = 0}, {_i < 5}, {_i = _i + 1}] do {}; hint str _i; // 5 // GOOD CODE (private keyword is recommended) _i = 100; for [{private _i = 0}, {_i < 5}, {_i = _i + 1}] do {}; hint str _i; // 100
Additional Information
- See also:
- Control Structureswhiledo
Notes
-
Report bugs on the Feedback Tracker and/or discuss them on the Arma Discord or on the Forums.
Only post proven facts here! Add Note
Notes
- Posted on 29 April 2010 (CEST)
- alef
for "_i" from 0 to 0 do {}; // will do once, with _i = 0 for "_i" from 0 to -1 do {}; // will not do- Posted on Apr 15, 2014 - 12:54
- ffur2007slx2_5
-
1.16 Please note the difference between the two syntaxes; for argumentsdetects Boolean in each scope whilefor arraydoesn’t. e.g.
command Structure Summary for array a = 0; b = true; for [{ _i = 0 }, { _i < 10 && b }, { _i = _i + 1 }] do { a = a + 1; if (a >= 7) then {b = false} }
loop can be exited via Boolean control, possible workaround can be e.g BIS_fnc_areEqual for arguments a = 0; for "_i" from 0 to 10 do { a = a + 1; if (a >= 7) exitwith {} };
has to be exited via exitWith
- Never try to tell a decimal number via binary number in a loop; otherwise the loop will be infinite:
for [{_a = 0},{_a != 1},{_a = _a + 0.1}] do {}; // an infinite loop; _a will never be 1 so the scope will always be trueAny binary number behind the decimal point is always the sum of 1/2, 1/4, 1/8, 1/16 etc. so decimal number with odd denominator like 1/3 or 1/10 cannot be exactly equal to each other.- Avoid too large factorial multiply which may loose the leading indicator in result. And 12 is the biggest accessable factor in this example.
for [{_a = 2; _b = 1;},{_a < 100},{_a = _a + 1}] do {_b = _b * _a}; // _b = 1.#INF - Posted on June 4, 2015 - 19:27 (UTC)
- Killzone Kid
-
Variable name doesn't have to start with _. could be:
for "LAlala" from 0 to 0 do {hint str LAlala}; // 0The variable LAlala will exist only inside do {} scope and will not overwrite any variable of the same name that existed before. - Posted on June 4, 2015 - 19:45 (UTC)
- Nickorr
-
Dont use this notation if you plan to change the cycle ranges dynamically. The range values are checked only before the cycle started. Use
for arrayinstead.
Example, that won't work correctly:_xy = [1,2,3,4,5,6,7,8,9,10]; for "_i" from 0 to (count _xy - 1) do { if ( _xy select _i == 3 ) then { _xy deleteAt _i; _i = _i - 1; }; };(Here the _i = 9 step will still be checked by the cycle, which will lead to "out of the array range" error.)
This code will work correctly:_xy = [1,2,3,4,5,6,7,8,9,10]; for [{_i=1},{_i<=(count _xy - 1)},{_i=_i+1}] do { if ( _xy select _i == 3 ) then { _xy deleteAt _i; _i = _i - 1; }; };(The last step here will be _i = 8 with array looking like this: [1,2,4,5,6,7,8,9,10]) - Posted on January 29, 2016 - 05:18 (UTC)
- DreadedEntity
-
For loops can be safely nested. This means that there should not be any problems with recursion.
_array = []; for "_i" from 0 to 3 do { for "_i" from 0 to 3 do { _array pushBack _i; }; _array pushBack _i; }; hint str _array; - Posted on June 3, 2020 - 11:45
- Lou Montana
- There is an Arma 2 issue (not present in Arrowhead nor in Arma 3) where having a capital letter in the variable name will throw an error:
for "_i" from 0 to 2 do { hintSilent str _i; }; // works for "_I" from 0 to 2 do { hintSilent str _I; }; // "variable _i is not defined" error