Exception handling: Difference between revisions

Latest revision as of 18:15, 7 January 2026

Armed Assault introduced exception handling through the try, catch and throw scripting commands, allowing scripts to create and react to exceptions.

Standard structure:

try // code block that can throw exception { if (_name == "") then { throw "no name"; }; // this exits the try block and enters the catch block below if (_name == "") throw "no name"; // since Arma 3 v1.54 titleText [format ["Good morning, Captain %1.", _name], "PLAIN DOWN"]; } catch // code block that processes an exception { if (_exception == "no name") then { hint "Name was not entered"; titleText ["Good morning, anonymous Captain.", "PLAIN DOWN"]; }; };

⚠

Real Virtuality scripting commands do not create SQF exceptions by themselves if they encounter an illegal situation,

they throw a compilation exception that cannot be caught by this try-catch structure explained here.

The following would therefore not create a catchable exception:

_divider = 0; try { a = 1 / _divider; } // SQF error happens here already catch { hint "illegal operation"; }; // useless

The proper way:

_divider = 0; try { if (_divider == 0) then { throw "div0"; }; a = 1 / _divider; } catch { hint "illegal operation"; };

@@ Line 1: / Line 1: @@
-In {{arma1}} exception handling is an implemented system of special scripting commands ([[try]], [[catch]] and [[throw]]), which allows your scripts to create and to react to exceptions.
+{{GVI|arma1|1.00}}
-Standard construction is:
+{{arma1}} introduced exception handling through the [[try]], [[catch]] and [[throw]] scripting commands, allowing scripts to create and react to exceptions.
- [[try]]
+Standard structure:
- {
+<sqf>
- 	{{cc|code block that can throw exception}}
+try		// code block that can throw exception
- 	[[if]] (_name == "") [[then]]
+{
- 	{
+	if (_name == "") then { throw "no name"; };	// this exits the [[try]] block and enters the [[catch]] block below
- 		[[throw]] "no name"
+	if (_name == "") throw "no name";			// since {{arma3}} v1.54
- 	}
- 	[[else]]
- 	{
- 		[[titleText]] [[[format]] ["Good morning, Captain %1.", _name], "PLAIN DOWN"]
- 		~1
- 		[[titleText]] [_name, "PLAIN DOWN"]
- 	}
- }
- [[catch]]
- {
- 	{{cc|code block that processes an exception}}
- 	[[if]] (_exception == "no name") [[then]]
- 	{
- 		[[hint]] "Name was not entered"
- 		[[titleText]] ["And the name isn't", "PLAIN DOWN"]
- 	}
- };
-{{Feature|important|{{Name|arma1|short}} scripting commands do '''not''' create SQF exceptions by themselves if they encounter an illegal situation, they throw a compilation exception (i.e. the here-described exception handling cannot be usedfor error trapping).
+	titleText [format ["Good morning, Captain %1.", _name], "PLAIN DOWN"];
+}
+catch	// code block that processes an exception
+{
+	if (_exception == "no name") then
+	{
+		hint "Name was not entered";
+		titleText ["Good morning, anonymous Captain.", "PLAIN DOWN"];
+	};
+};
+</sqf>
+{{Feature|important|
+{{Name|rv}} scripting commands do '''not''' create SQF exceptions by themselves if they encounter an illegal situation,
+they throw a '''''compilation''''' exception that cannot be caught by this try-catch structure explained here.
 The following would therefore '''not''' create a catchable exception:
-<code>[[try]]<br>{<br>	a {{=}} 1/0; {{cc|SQF error happens here already}}<br>}<br>[[catch]]<br>{<br>	[[hint]] "illegal operation";<br>};</code>
+<sqf>
+_divider = 0;
+try		{ a = 1 / _divider; }			// SQF error happens here already
+catch	{ hint "illegal operation"; };	// useless
+</sqf>
+The proper way:
+<sqf>
+_divider = 0;
+try		{ if (_divider == 0) then { throw "div0"; }; a = 1 / _divider; }
+catch	{ hint "illegal operation"; };
+</sqf>
 }}
 [[Category: Scripting Topics]]
+[[Category:Introduced with Armed Assault version 1.00]]