Any PHP script is built out of a series of statements. A statement can be an assignment, a function call, a loop, a conditional statement of even a statement that does nothing (an empty statement). Statements usually end with a semicolon. In addition, statements can be grouped into a statement-group by encapsulating a group of statements with curly braces. A statement-group is a statement by itself as well.
An if statement is a way of controlling the execution of a statement that follows it (that is, a single statement or a block of code inside braces). The if statement evaluates an expression between parentheses. If this expression results in a true value, the statement is executed. Otherwise, the statement is skipped entirely. This enables scripts to make decisions based on any number of factors:
PHP Example:- The following code would display a is bigger than b if $a is bigger than $b:
When working with the if statement, you will often want to define an alternative block of code that should be executed if the expression you are testing evaluates to false. You can do this by adding else to the if statement followed by a further block of code:
PHP Example:- The following code would display a is bigger than b if $a is bigger than $b, and a is NOT bigger than b otherwise:
As its name suggests, is a combination of if and else. Like else, it extends an if statement to execute a different statement in case the original if expression evaluates to FALSE. However, unlike else, it will execute that alternative expression only if the elseif conditional expression evaluates to TRUE.
PHP Example:- The following code would display a is bigger than b, a equal to b or a is smaller than b:
The switch statement is similar to a series of IF statements on the same expression. In many occasions, you may want to compare the same variable (or expression) with many different values, and execute a different piece of code depending on which value it equals to. This is exactly what the switch statement is for.Tips:-
?Software is like entropy: It is difficult to grasp, weighs nothing, and obeys the Second Law of Thermodynamics; i.e., it always increases.
?Spreadsheet: a kind of program that lets you sit at your desk and ask all kinds of neat "what if?" questions and generate thousands of numbers instead of actually working.