PHP - Function extract()


extract($array, $extract_type, $prefix)

Definition and Usage

This function is used to import variables from an array into the current symbol table. It takes an associative array array and 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 extract_type and prefix parameters.


Sr.No Parameter & Description


It specifies an array



. The extract() function checks for invalid variable names and collisions with existing variable names. This parameter specifies how invalid and colliding names are treated.Possible values −

  • EXTR_OVERWRITE − Default. On collision, the existing variable is overwritten

  • EXTR_SKIP − On collision, the existing variable is not overwritten

  • EXTR_PREFIX_SAME − On collision, the variable name will be given a prefix

  • EXTR_PREFIX_ALL − All variable names will be given a prefix

  • EXTR_PREFIX_INVALID − Only invalid or numeric variable names will be given a prefix

  • EXTR_IF_EXISTS − Only overwrite existing variables in the current symbol table, otherwise do nothing

  • EXTR_PREFIX_IF_EXISTS − Only add prefix to variables if the same variable exists in the current symbol table

  • EXTR_REFS − Extracts variables as references. The imported variables are still referencing the values of the array parameter



If EXTR_PREFIX_SAME, EXTR_PREFIX_ALL, EXTR_PREFIX_INVALID or EXTR_PREFIX_IF_EXISTS are used in the extract_rules parameter, a specified prefix is required.

This parameter specifies the prefix. The prefix is automatically separated from the array key by an underscore character.

Return Value

It returns the number of variables successfully imported into the symbol table.


Try out following example −

   $size = "large";
   $input = array("color" => "blue", "size"  => "medium", "shape" => "sphere");
   extract($input, EXTR_PREFIX_SAME, "bbcx");
   echo "$color, $size, $shape, $bbcx_size";

This will produce the following result −

blue, large, sphere, medium
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