Which of the following are valid function names in php?

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• Which of the following are valid function names? 1. function() 2. €() 3. .function() 4. $function()
• Solution(By Examveda Team)
• Click here to read 1000+ Related Questions on Functions(PHP)
• Join The Discussion
• Which of the function are valid function names?
• What are functions in PHP?
• What is type of function in PHP?
• Which of the following valid functions call?

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Which of the following are valid function names? 1. function() 2. €() 3. .function() 4. $function()

A. Only 2

B. None of the mentioned

C. All of the mentioned

D. 3 and 4

Answer: Option A

Solution(By Examveda Team)

Except a) others are invalid names. According to the specified regular expression ([a-zA-Z_x7f-xff][a-zA-Z0-9_x7f-xff]*), a function name like this one is valid.

Click here to read 1000+ Related Questions on Functions(PHP)

Join The Discussion

A function may be defined using syntax such as the following:

Example #1 Pseudo code to demonstrate function uses

function foo($arg_1, $arg_2, /* ..., */ $arg_n)
{
    echo "Example function.\n";
    return $retval;
}
?>

Any valid PHP code may appear inside a function, even other functions and class definitions.

Function names follow the same rules as other labels in PHP. A valid function name starts with a letter or underscore, followed by any number of letters, numbers, or underscores. As a regular expression, it would be expressed thus: ^[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*$.

Functions need not be defined before they are referenced, except when a function is conditionally defined as shown in the two examples below.

When a function is defined in a conditional manner such as the two examples shown. Its definition must be processed prior to being called.

Example #2 Conditional functions

$makefoo

Example #3 Functions within functions

function foo() 
{
  function bar() 
  {
    echo "I don't exist until foo() is called.\n";
  }
}/* We can't call bar() yet
   since it doesn't exist. */foo();/* Now we can call bar(),
   foo()'s processing has
   made it accessible. */bar();?>

All functions and classes in PHP have the global scope - they can be called outside a function even if they were defined inside and vice versa.

PHP does not support function overloading, nor is it possible to undefine or redefine previously-declared functions.

Note: Function names are case-insensitive for the ASCII characters A to Z, though it is usually good form to call functions as they appear in their declaration.

Both variable number of arguments and default arguments are supported in functions. See also the function references for func_num_args(), func_get_arg(), and func_get_args() for more information.

It is possible to call recursive functions in PHP.

Example #4 Recursive functions

function recursion($a)
{
    if ($a < 20) {
        echo "$a\n";
        recursion($a + 1);
    }
}
?>

Note: Recursive function/method calls with over 100-200 recursion levels can smash the stack and cause a termination of the current script. Especially, infinite recursion is considered a programming error.

Which of the function are valid function names?

What are functions in PHP?

What is type of function in PHP?

Which of the following valid functions call?