PHP syntax basics, php syntax _ PHP Tutorial

PHP syntax basics: php syntax. PHP syntax basics: php syntax 1. PHP syntax basics $ a10; variables can be modified during running $ a10; $ a20; $ b5; echo $ a + $ B; constTHE_VALUE100; constants can only be assigned PHP syntax basics, php syntax
1. PHP syntax basics

• $ A = 10; variables can be modified during running

$a = 10;$a = 20;$b = 5;echo $a+$b;

• Const THE_VALUE = 100; a constant can only be assigned once; otherwise, a syntax error is reported.

Const THE_VALUE = 100; // THE_VALUE = 200; an echo THE_VALUE error is returned when a syntax error occurs;

• Method for defining constants in PHP4

Define ('The _ value', 200); // THE_VALUE = 200; syntax error echo THE_VALUE;

2. the Function encapsulates a lot of functional code blocks.

• Simple functions

function traceHelloPHP(){    echo 'Hello PHP';    echo '
';    echo 'Hello World';}traceHelloPHP();

• Use a function as a callback for other functions

function traceHelloPHP(){    echo 'Hello PHP——back';    echo '
';    echo 'Hello World';}//traceHelloPHP(); $func = 'traceHelloPHP';$func();

• Function input parameters

function sayHello($name){    echo 'Hello '.$name;    echo '
';}sayHello('ZhangSan');sayHello('Lisi');

• Multiple Input parameter functions

Function traceNum ($ a, $ B) {echo 'a = '. $ a.', B = '. $ B .'
'; Echo "a = $ a, B = $ B
"; // This write is also possible} traceNum (2, 3 );

• Functions with return values

function add($a,$b){    return $a+$b;}echo add(10,2).'
';

3. Process control

• Cause of garbled characters: the server encoding method is different from the client encoding method. Solution: add the html header and embed the php code into the body.

    
     Control Flow
 = 90) {return 'excellent ';} elseif ($ score> = 80) {return 'good';} elseif ($ score >=70) {return 'good ';} elseif ($ score> = 60) {return 'can';} else {return 'differential';} echo getLevel (92 ).'
';?>

• Control statement syntax 2

Function getLevel_switch ($ score) {switch ($ score/10) {case 10: case 9: return 'excellent '; case 8: return 'good'; case 7: return 'good'; case 6: return' can be '; default: return 'bad' ;}} echo getLevel_switch (60 ).'
';

• Control statement writing 3

Function getLevel_break ($ score) {$ result = '--'; switch (intval ($ score/10) {case 10: case 9: $ result = 'excellent '; break; case 8: $ result = 'good'; break; case 7: $ result = 'good'; break; case 6: $ result = 'OK'; break ;} return $ result;} echo getLevel_break (83 ).'
';

4. Loop

• For loop

for($i=0;$i<100;$i++){    echo 'Hello '.$i.'
';}

• While loop first judgment and then execution

$i = 0;while($i < 50){    echo 'Hello '.$i.'
';    $i++;}

• The do-while loop is first executed in the judgment

$ I = 0; do {echo 'hello'. $ I .'
'; $ I ++; // do not forget auto-increment; otherwise, an endless loop will be programmed.} while ($ I <20 );

• Break quits* Entire *Loop

for($i=0;$i<100;$i++){    echo 'Hello '.$i.'
';    if( $i == 20 ){        break;    }}

• Continue jump out* This time *Loop

for($i=0;$i<100;$i++){    echo 'Hello '.$i.'
';//    if( $i == 20 ){//        break;//    }    if(20 == $i){        continue;    }    echo 'Run here '.$i.'
';}

5. logical operations and & | not!

function traceNum(){    for($i=0;$i<=100;$i++){//        if(0 == $i%2 && 0==$i%3){//            echo $i.'
';//        }//        if(0 == $i%2 || 0==$i%3){//            echo $i.'
';//        }        if(!(0 == $i%2)){            echo $i.'
';        }    }}traceNum();

Lifecycle 1. PHP syntax basics $ a = 10; variables can be modified during running $ a = 10; $ a = 20; $ B = 5; echo $ a + $ B; const THE_VALUE = 100; constants can only be assigned values...