create_function Create an anonymous (lambda-style) function &reftitle.description; stringcreate_function stringargs stringcode Creates an anonymous function from the parameters passed, and returns a unique name for it. &reftitle.parameters; Usually these parameters will be passed as single quote delimited strings. The reason for using single quoted strings, is to protect the variable names from parsing, otherwise, if you use double quotes there will be a need to escape the variable names, e.g. \$avar. args The function arguments. code The function code. &reftitle.returnvalues; Returns a unique function name as a string, or &false; on error. &reftitle.examples; You can use this function, to (for example) create a function from information gathered at run time: ]]> Or, perhaps to have general handler function that can apply a set of operations to a list of parameters: =0) {return "b*a^2 = ".$b*sqrt($a);} else {return false;}'; $f2 = "return \"min(b^2+a, a^2,b) = \".min(\$a*\$a+\$b,\$b*\$b+\$a);"; $f3 = 'if ($a > 0 && $b != 0) {return "ln(a)/b = ".log($a)/$b; } else { return false; }'; $farr = array( create_function('$x,$y', 'return "some trig: ".(sin($x) + $x*cos($y));'), create_function('$x,$y', 'return "a hypotenuse: ".sqrt($x*$x + $y*$y);'), create_function('$a,$b', $f1), create_function('$a,$b', $f2), create_function('$a,$b', $f3) ); echo "\nUsing the first array of anonymous functions\n"; echo "parameters: 2.3445, M_PI\n"; process(2.3445, M_PI, $farr); // now make a bunch of string processing functions $garr = array( create_function('$b,$a', 'if (strncmp($a, $b, 3) == 0) return "** \"$a\" '. 'and \"$b\"\n** Look the same to me! (looking at the first 3 chars)";'), create_function('$a,$b', '; return "CRCs: " . crc32($a) . " , ".crc32(b);'), create_function('$a,$b', '; return "similar(a,b) = " . similar_text($a, $b, &$p) . "($p%)";') ); echo "\nUsing the second array of anonymous functions\n"; process("Twas brilling and the slithy toves", "Twas the night", $garr); ?> ]]> &example.outputs; But perhaps the most common use for of lambda-style (anonymous) functions is to create callback functions, for example when using array_walk or usort ]]> &example.outputs; the mango [1] => a mango [2] => that mango [3] => this mango ) ]]> an array of strings ordered from shorter to longer ]]> &example.outputs; small [1] => larger [2] => a big string [3] => it is a string thing ) ]]> sort it from longer to shorter ]]> &example.outputs; it is a string thing [1] => a big string [2] => larger [3] => small ) ]]>