How to use member functions in an if statement in PHP

If I have a function called name(), I can check if (name()) {}, and if name() evaluates to true then the body of the if is executed开发者_开发知识库.

But with a class like this:

$miniaturas = new miniaturas();
$miniaturas->thumb($db);

If I try:

if (thumb($miniaturas->thumb($db))) { }

Or this:

if (thumb($db)) {}

I get:

Fatal error: Call to undefined function thumb() .

How can I call this function in a class like I do for functions outside a class?

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It's just if ($miniaturas->thumb($db)) { ... }. This is because you defined thumb() as a member function to the class miniaturas, and because it's a member of that class it's not a member of the global namespace.

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if (thumb($miniaturas->thumb($db))) {}

Unless you actually have a function named thumb you want

if ($miniaturas->thumb($db)) {}

The extra function call to thumb is what is breaking

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try this:

if(function_exists("$miniaturas->thumb"))

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in addition to the comment from Neal, the I check for method/function existance using the following php builtin functions:

1. function_exists: I use this one to see if a plain function exists

   if (function_exists('thumb')) { thumb($db); }

2. method_exists: I prefer to use that one if I have to check for "methods" of objects

   $miniaturas = new miniaturas();

   if (method_exists($miniaturas, 'thumb')) { $miniaturas->thumb($db); }

In addition to that you also can use is_callable, which checks whether a function/method is callable ... take a look at

doc for function_exists

doc for method_exists

doc for is_callable

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i think you want if ($miniaturas->thumb($db)) { // code } and the method thumb should return a boolean

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The function_exists() function is used to determine whether or not a function exists:

if (function_exists('thumb')){
  //...
}