Basic Input Testing in PHP

 Basic Input Testing in PHP

• PHP provides various Testing Functions for Basic Input Testing.
• These functions are very important for professional development.
• If the program is used without checking the value, then somewhere the program crashes and the project fails, and impossible to find a bug.
•  PHP functions provide to test the value of any kind of Data Type Identifier i.e. Variable at any time are very important functions.

Basically, all Testing Functions always return a Boolean value.

isset() function

• This Function accepts Mixed Type Variables with the Number of Arguments. 
• This function checks that the specified variables as arguments are set to a value and are not NULL.
• If the specified variable as an argument is set to a value other than NULL, then this function returns true otherwise it returns False.

empty() Language Construct

• This function tests whether the specified variable as an argument is Empty or not.
• It works in the Exact Opposite way of Function (boolean)$var Expression.

array() (to Empty Array)

• Declared but Uninitialized/Unassigned Data Member in a Class.
• The basic difference between both empty() and isset() is that empty() checks whether the values ​​which are considered Empty in PHP are stored in the variable other than those Empty Values ​​or not.

unset() Function

• This Function accepts a Variable Number of Arguments as Arguments. 
• The main work of this function is to destroy the specified variable in the form of an Argument.
• When unset() a Global Variable inside a Function, then that Variable is unset only inside that Function, and remains available outside the Function. That is, Destroying Local variables and Global variables.
• To Destroy Global Variable,  use Unset that Variable from $GLOBAL Array, which is Destroy Permanently from our script.
• If pass a reference to a variable in a function and unset that variable in that function, then that variable is destroyed only for the function. 
• That function is still available outside the function.
• When unset a Static Variable inside a Function, then that Static Variable is also Destroy only for that Function.
• If the __unset () magic method is defined and calls the unset() function for an inaccessible object property, then this magic method gets called automatically.

 is_ Functions

• Used to test the variables of different data types whether they belong to that data type or not.
• The different is_ functions are as follows:

is_array() Function

The is_array() function checks whether a variable is an array or not. This function returns true (1) if the variable is an array, otherwise, it returns false/nothing.

is_double() Function

The is_double() function checks whether a variable is of type float or not. This function is an alias of is_float().

is_float() Function

The is_float() function checks whether a variable is of type float or not. This function returns true (1) if the variable is of type float, otherwise, it returns false.

is_int() Function

The is_int() function checks whether a variable is of type integer or not.

This function returns true (1) if the variable is of type integer, otherwise, it returns false.

is_null() Function

The is_null() function checks whether a variable is NULL or not. This function returns true (1) if the variable is NULL, otherwise, it returns false/nothing.

is_object() Function

The is_object() function checks whether a variable is an object. This function returns true (1) if the variable is an object, otherwise, it returns false/nothing.

is_string() Function

The is_string() function checks whether a variable is of type string or not. This function returns true (1) if the variable is of type string, otherwise, it returns false/nothing.

is_callable() Function

The is_callable() function checks whether the contents of a variable can be called a function or not. This function returns true (1) if the variable is callable, otherwise, it returns false/nothing.

 The header function

• Allows sending a raw HTTP header. It is useful for handling security problems and access restrictions.
• In this instance, it redirects the user to the specified page.
• A very common error with beginning PHP users is that they fail to understand a fact: Once sent, the headers cannot be sent again.
• This means that any echo, any space, or any tabulation left before the call to the header function will trigger a warning in the script execution.

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