PHP DAY 6 ( Flow control and Loops, break statement, continue statement )

DAY - 6

Flow control and Loops

PHP supports following three decision making (Flow control ) statements –

·        if...else statement − use this statement if you want to execute a set of code when a condition is true and another if the condition is not true

·        elseif statement − is used with the if...else statement to execute a set of code if one of the several condition is true

·        switch statement − is used if you want to select one of many blocks of code to be executed, use the Switch statement. The switch statement is used to avoid long blocks of if..elseif..else code.

The If...Else Statement

If you want to execute some code if a condition is true and another code if a condition is false, use the if....else statement.

Syntax

if (condition)

code to be executed if condition is true;

else

code to be executed if condition is false;

 

The ElseIf Statement

If you want to execute some code if one of the several conditions are true use the elseif statement

Syntax

if (condition)

code to be executed if condition is true;

elseif (condition)

code to be executed if condition is true;

else

code to be executed if condition is false;

 

The Switch Statement

If you want to select one of many blocks of code to be executed, use the Switch statement.

The switch statement is used to avoid long blocks of if..elseif..else code.

Syntax

switch (expression){

   case label1:

code to be executed if expression = label1;

      break;  

   case label2:

code to be executed if expression = label2;

      break;

      default:

code to be executed

   if expression is different 

   from both label1 and label2;

}

 

Loops in PHP are used to execute the same block of code a specified number of times. PHP supports following four loop types.

·        for − loops through a block of code a specified number of times.

·        while − loops through a block of code if and as long as a specified condition is true.

·        do...while − loops through a block of code once, and then repeats the loop as long as a special condition is true.

·        foreach − loops through a block of code for each element in an array.

 

The for loop statement

The for statement is used when you know how many times you want to execute a statement or a block of statements.

Syntax

for (initialization; condition; increment){

code to be executed;

}

The initializer is used to set the start value for the counter of the number of loop iterations. A variable may be declared here for this purpose and it is traditional to name it $i.

 

The while loop statement

The while statement will execute a block of code if and as long as a test expression is true.

If the test expression is true then the code block will be executed. After the code has executed the test expression will again be evaluated and the loop will continue until the test expression is found to be false.

Syntax

while (condition) {

code to be executed;

}

 

 

The do...while loop statement

The do...while statement will execute a block of code at least once - it then will repeat the loop as long as a condition is true.

Syntax

do {

code to be executed;

}

while (condition);

 

 

The foreach loop statement

The foreach statement is used to loop through arrays. For each pass the value of the current array element is assigned to $value and the array pointer is moved by one and in the next pass next element will be processed.

Syntax

foreach (array as value) {

code to be executed;

}

 

 

The break statement

The PHP break keyword is used to terminate the execution of a loop prematurely.

The break statement is situated inside the statement block. It gives you full control and whenever you want to exit from the loop you can come out. After coming out of a loop immediate statement to the loop will be executed.

 

 

 

The continue statement

The PHP continue keyword is used to halt the current iteration of a loop but it does not terminate the loop.

Just like the break statement the continue statement is situated inside the statement block containing the code that the loop executes, preceded by a conditional test. For the pass encountering continue statement, rest of the loop code is skipped and next pass starts.