Three main flow control of PHP program

Three main flow control of PHP program

① sequential control (from top to bottom, left to right)

② Branch Control

if (conditional expression) {

N Multiple statements

}else if (conditional expression) {

N Multiple statements

}else if (conditional expression) {

//.

}//there may be more else if

else{

}

U Switch Branch statement

Basic grammatical structure

switch (expression) {

CASE constant 1:

n multiple statements;

Break

Case constant 2:

N Multiple statements

Break

Default

n multiple statements;

Break

}

the type of the U constant (int, float, string, Boolean, and null

You can keep the default wherever you go.

The right side will output hello12.

Conclusion: first match according to case order, if none of them match

, the default is executed until a break is encountered or}

Application scenario: When our branch is a few points (for example, to determine the direction of a tank), you should use Swtich, and if your branch is judged by several areas (ranges), consider using IF.

③ Cycle Control Process

For (cyclic initial value; loop condition; step size) {

n multiple statements;

}

while (loop condition) {

Loop body, statement

}

do{

Circulation body

}while (cyclic conditions);

42, we in accordance with the normal thinking should be guaranteed to accept the data when $_request[' parameters ' to the submission of data page to give the name of the HTML element to be consistent. If it is inconsistent, a notice prompt appears. And the data we accept is null, equivalent to "".

$_request This method can accept the user's post or GET request data

43. Break and Continue

U -Loop related statements-break

Basic concept: Represents the end of the current for, while, do. While, switch, process, you can give a number that represents the exit to the first level.

$i = 0;

while (+ + $i) {

Switch ($i) {

Case 5:

Echo Quit AT5
;

Break

Case 10:

Echo Quitat 10
;

Break 2;

Default

Break

}

}

echo ' $i = '. $i;

The result:

Quit at 5
Quit at 10
$i =10

From the above case, we have several conclusions:

1. Break statement default jump out of 1 layer

2. The number after the break statement, can not exceed the actual number of loops to jump out, otherwise, will report FatalError

Ø Circular related statements-continue

Basic concept: Continue is used to end this cycle of remaining code, to start a new cycle (if the condition is true, continue to execute), continue can also be followed by a number, indicating from the first several loops restart