extract

PHP 4, PHP 5, PHP 7, PHP 8
extract - Import variables into the current symbol table from an array
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extract( arrayarray, [int$flags = EXTR_OVERWRITE], [string$prefix = ""] ): int

Import variables from an array into the current symbol table.

Checks each key to see whether it has a valid variable name. It also checks for collisions with existing variables in the symbol table.

Warning:

Do not use extract on untrusted data, like user input (e.g. $_GET, $_FILES).

Parameters

array

An associative array. This function treats keys as variable names and values as variable values. For each key/value pair it will create a variable in the current symbol table, subject to flags and prefix parameters.

You must use an associative array; a numerically indexed array will not produce results unless you use EXTR_PREFIX_ALL or EXTR_PREFIX_INVALID.

flags

The way invalid/numeric keys and collisions are treated is determined by the extraction flags. It can be one of the following values:

EXTR_OVERWRITE

If there is a collision, overwrite the existing variable.

EXTR_SKIP

If there is a collision, don't overwrite the existing variable.

EXTR_PREFIX_SAME

If there is a collision, prefix the variable name with prefix.

EXTR_PREFIX_ALL

Prefix all variable names with prefix.

EXTR_PREFIX_INVALID

Only prefix invalid/numeric variable names with prefix.

EXTR_IF_EXISTS

Only overwrite the variable if it already exists in the current symbol table, otherwise do nothing. This is useful for defining a list of valid variables and then extracting only those variables you have defined out of $_REQUEST, for example.

EXTR_PREFIX_IF_EXISTS

Only create prefixed variable names if the non-prefixed version of the same variable exists in the current symbol table.

EXTR_REFS

Extracts variables as references. This effectively means that the values of the imported variables are still referencing the values of the array parameter. You can use this flag on its own or combine it with any other flag by OR'ing the flags.

If flags is not specified, it is assumed to be EXTR_OVERWRITE.

prefix

Note that prefix is only required if flags is EXTR_PREFIX_SAME, EXTR_PREFIX_ALL, EXTR_PREFIX_INVALID or EXTR_PREFIX_IF_EXISTS. If the prefixed result is not a valid variable name, it is not imported into the symbol table. Prefixes are automatically separated from the array key by an underscore character.

Return Values

Returns the number of variables successfully imported into the symbol table.

Notes

Warning:

Do not use extract on untrusted data, like user input (i.e. $_GET, $_FILES, etc.). If you do, make sure you use one of the non-overwriting flags values such as EXTR_SKIP and be aware that you should extract in the same order that's defined in variables_order within the php.ini.

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Function extract:

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