How to determine variable type in PHP function?

In PHP, you can obtain the variable type through the gettype() function, which returns type information in the form of a string, such as string, integer, etc. In addition, the is_* function series can be used to determine specific types, such as is_string() to determine whether it is a string.

#How to determine variable type in PHP function?

In PHP, the most convenient way to determine the type of a variable is to use the gettype() function. This function returns a string representing the type of the variable. Here are some examples:

$variable = 'string';
echo gettype($variable); // 输出：string

$variable = 123;
echo gettype($variable); // 输出：integer

$variable = 123.45;
echo gettype($variable); // 输出：double

$variable = true;
echo gettype($variable); // 输出：boolean

$variable = [];
echo gettype($variable); // 输出：array

$variable = new stdClass();
echo gettype($variable); // 输出：object

In addition to the gettype() function, PHP also provides the is_* family of functions for testing specific types. For example:

$variable = 'string';
if (is_string($variable)) {
  echo '变量是字符串';
}

Practical case

Suppose we have an array containing elements of different types, and we want to classify the array based on the type. We can use the following function:

function categorizeVariables(array $variables): array
{
  $categorizedVariables = [];

  foreach ($variables as $key => $variable) {
    switch (gettype($variable)) {
      case 'string':
        $categorizedVariables['strings'][$key] = $variable;
        break;
      case 'integer':
        $categorizedVariables['integers'][$key] = $variable;
        break;
      case 'double':
        $categorizedVariables['doubles'][$key] = $variable;
        break;
      case 'boolean':
        $categorizedVariables['booleans'][$key] = $variable;
        break;
      case 'array':
        $categorizedVariables['arrays'][$key] = $variable;
        break;
      case 'object':
        $categorizedVariables['objects'][$key] = $variable;
        break;
    }
  }

  return $categorizedVariables;
}

In the above example, the categorizeVariables function will return a function that classifies the array elements into different categories (String, Integer, Double, Boolean , arrays and objects) associative arrays.

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