The variable $history does not seem to be defined for all execution paths leading up to this point.
If you define a variable conditionally, it can happen that it is not defined
for all execution paths.
Let’s take a look at an example:
functionmyFunction($a){switch($a){case'foo':$x=1;break;case'bar':$x=2;break;}// $x is potentially undefined here.echo$x;}
In the above example, the variable $x is defined if you pass “foo” or “bar”
as argument for $a. However, since the switch statement has no default
case statement, if you pass any other value, the variable $x would be undefined.
Available Fixes
Check for existence of the variable explicitly:
functionmyFunction($a){switch($a){case'foo':$x=1;break;case'bar':$x=2;break;}if(isset($x)){// Make sure it's always set.echo$x;}}
Define a default value for the variable:
functionmyFunction($a){$x='';// Set a default which gets overridden for certain paths.switch($a){case'foo':$x=1;break;case'bar':$x=2;break;}echo$x;}
Add a value for the missing path:
functionmyFunction($a){switch($a){case'foo':$x=1;break;case'bar':$x=2;break;// We add support for the missing case.default:$x='';break;}echo$x;}
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Greg Sabino Mullane
Alexander Emsenhuber
Siebrand Mazeland
If you define a variable conditionally, it can happen that it is not defined for all execution paths.
Let’s take a look at an example:
In the above example, the variable $x is defined if you pass “foo” or “bar” as argument for $a. However, since the switch statement has no default case statement, if you pass any other value, the variable $x would be undefined.
Available Fixes
Check for existence of the variable explicitly:
Define a default value for the variable:
Add a value for the missing path: