PHP switch statement syntax examples and efficiency comparisons with IfElse

The switch statement is also the longest common logical control statement in object-oriented programming statements. The Switch statement is used to perform different actions based on multiple different conditions-that is, when the conditions are different, perform different logical operations. It is similar to the switch usage in other statements, but notice there is a break statement.

Standard syntax for switch statements in PHP:

switch (expression) {case Label1:code to being executed if expression = Label1; break; case Label2:code to be executed if ex pression = Label2; Break;default:code to being executed if expression is different from both Label1 and Label2;}

Example:

Switch ($i) {case  1:    echo 1;    break;  Case 2:    Echo 2;    break;  Default:    echo ' others ';}

You can also use switch to determine a range of values, or to customize conditions in a case.

<?phpheader ("Content-type:text/html;charset=utf8"); $score =50;switch ($score) {case $score >=90 && $ SCORE<=100:  echo "excellent <br>";  Break Case $score >=80 && $score <90:  echo "Liang <br>";  Break Case $score >=70 && $score <80:  echo "in <br>";  Break Case $score >=60 && $score <70:  echo "pass <br>";  Break Case $score >=0 && $score <60:  echo "inferior lattice <br>";  Break Default:  echo "score input error <br>";}? >

Simple example

<?php//switch Details//Case one: When the numeric match is automatically converted into a string $a = 1;     Switch ($a) {case "1": Echo ' hello1 ';   Break     Default:echo ' Sorry none is the same! ';  Break } Echo ' <br/> '.  Successful exit ";   Echo ' 
Run results

Hello1 Successful exit Hello2 Successful exit Hello3 Successful exit Hello4 Successful exit Hello5 Successful exit Hello6 Successful exit Hello7 Successful exit Hello81 Successful exit I'm exit 5th, Hello61 successfully quit. Hello6, I'm exit 2nd.
Regardless of the language of the program, will certainly take into account the operational efficiency of the Code. After reviewing some of the information, switch and ifelse in different ' environment ' efficiency each has the superiority.

1, when the value to be judged is a constant (fixed value), the operation efficiency of switch is higher than that of IfElse.

$changliang =3;   The value of variable judgment is constant switch ($changliang) {case  1:    echo ' constant value is 1 ';    break;   Jump out  of the Loop Case 2:    echo ' constant value is 2 ';    break;  Case 3:    echo ' constant value is 3 ';    break;}
2, when judged value as a variable, ifelse operating efficiency is higher than switch,ifelse implementation of the policy, will start judging from the first condition, until the last else, so learn to use switch has the advantage;

$a = $_get[' a ']; Pass value after get pass value; The value of the evaluated if ($a =1) {  echo ' variable A is 1 ';} ElseIf ($a =2) {  echo ' variable A has a value of 2 ';} ElseIf ($a =3) {  echo ' variable A has a value of 3 ';} else{  Echo ' variable A's value is not known ';}