Which PHP function is used to check if a function exists before calling it?

What is the output of the following PHP code?
<?php
function outer() {
function inner() {
echo 'Inner function';
}
}
inner();
?

A). Inner function

B). Function does not exist: inner

C). Undefined function: inner

D). Function inner() { echo 'Inner function'; }

What will be the output of the following PHP code?
<?php
function sum($a, $b = 5) {
return $a + $b;
}
echo sum(3);
?

A). 3

B). 8

C). 5

D). Function call will result in an error

What is the significance of passing functions as arguments in PHP?

A). It allows functions to be called multiple times

B). It simplifies the function definition process

C). It enables dynamic function invocation and behavior

D). It prevents code duplication

What will be the output of the following PHP code?
<?php
function factorial($n) {
$result = 1;
for ($i = 1; $i <= $n; $i++) {
$result *= $i;
}
return $result;
}
echo factorial(5);
?

A). 120

B). 5

C). Undefined function: factorial

D). Function factorial($n) { $result = 1; for ($i = 1; $i <= $n; $i++) { $result *= $i; } return $result; }

Which PHP feature allows defining functions with variable-length argument lists?

A). Dynamic functions

B). Variable arguments

C). Varargs

D). All of the above

Which PHP feature allows specifying default values for function arguments?

A). Default arguments

B). Optional parameters

C). Variable-length argument lists

D). All of the above

Which PHP feature allows defining functions within other functions?

A). Inner functions

B). Enclosed functions

C). Nested functions

D). All of the above

What is the purpose of the return statement in PHP functions?

A). To output a value from the function and terminate its execution

B). To specify the return type of the function

C). To declare a variable within the function

D). To terminate the function execution

Which PHP keyword is used to pass a function as an argument to another function?

A). Dynamic functions

B). Anonymous functions

C). Callbacks

D). All of the above

What is the output of the following PHP code?
<?php
function uppercase($str) {
return strtoupper($str);
}
echo uppercase('hello');
?

A). HELLO

B). hello

C). Uppercase

D). Undefined function: uppercase