PHP语法基础，php语法
1.PHP语法基础- $a = 10; 变量 可以在运行过程中修改
<span>$a</span> = 10<span>; </span><span>$a</span> = 20<span>; </span><span>$b</span> = 5<span>; </span><span>echo</span> <span>$a</span>+<span>$b</span>;
- const THE_VALUE = 100; 常量 只能被赋值一次，否则会报语法错误
<span>const</span> THE_VALUE = 100<span>; </span><span>//</span><span>THE_VALUE = 200; 有语法错误 运行时会报错</span> <span>echo</span> THE_VALUE;
- 在PHP4中定义常量的方法
<span>define</span>('THE_VALUE',200<span>);
</span><span>//</span><span>THE_VALUE = 200; 有语法错误</span>
<span>echo</span> THE_VALUE;
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- 简单函数
<span>function</span><span> traceHelloPHP(){
</span><span>echo</span> 'Hello PHP'<span>;
</span><span>echo</span> '<br/>'<span>;
</span><span>echo</span> 'Hello World'<span>;
}
traceHelloPHP();</span>- 将函数作为其它函数的回调函数
<span>function</span><span> traceHelloPHP(){
</span><span>echo</span> 'Hello PHP——back'<span>;
</span><span>echo</span> '<br/>'<span>;
</span><span>echo</span> 'Hello World'<span>;
}
</span><span>//</span><span>traceHelloPHP();</span>
<span>$func</span> = 'traceHelloPHP'<span>;
</span><span>$func</span>();- 函数的传入参数
<span>function</span> sayHello(<span>$name</span><span>){
</span><span>echo</span> 'Hello '.<span>$name</span><span>;
</span><span>echo</span> '<br/>'<span>;
}
sayHello(</span>'ZhangSan'<span>);
sayHello(</span>'Lisi');- 多个传入参数的函数
<span>function</span> traceNum(<span>$a</span>,<span>$b</span><span>){
</span><span>echo</span> 'a = '.<span>$a</span>.' , b = '.<span>$b</span>.'<br/>'<span>;
</span><span>echo</span> "a = <span>$a</span> , b = <span>$b</span><br/>"; <span>//</span><span>这样写也是可以的</span>
<span>}
traceNum(</span>2,3);- 带有返回值的函数
<span>function</span> add(<span>$a</span>,<span>$b</span><span>){
</span><span>return</span> <span>$a</span>+<span>$b</span><span>;
}
</span><span>echo</span> add(10,2).'<br>';
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3.流程控制- 出现乱码的原因：服务器的编码方式和客户端的编码方式不同 解决办法：添加html头，并将php代码嵌入body中
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Control Flow</title>
</head>
<body>
<?<span>php
</span><span>/*</span><span>*
* Created by PhpStorm.
* User: Administrator
* Date: 2015/11/10
* Time: 16:07
</span><span>*/</span>
<span>function</span> getLevel(<span>$score</span><span>){
</span><span>if</span>(<span>$score</span> >= 90<span>){
</span><span>return</span> '优秀'<span>;
}</span><span>elseif</span>(<span>$score</span> >= 80<span>){
</span><span>return</span> '良好'<span>;
}</span><span>elseif</span>(<span>$score</span> >= 70<span>){
</span><span>return</span> '好'<span>;
}</span><span>elseif</span>(<span>$score</span> >= 60<span>){
</span><span>return</span> '可以'<span>;
}</span><span>else</span><span> {
</span><span>return</span> '差'<span>;
}
}
</span><span>echo</span> getLevel(92).'<br/>'<span>;
</span>?>
</body>
</html>- 控制语句写法2
<span>function</span> getLevel_switch(<span>$score</span><span>){
</span><span>switch</span>(<span>$score</span>/10<span>){
</span><span>case</span> 10:
<span>case</span> 9:
<span>return</span> '优秀'<span>;
</span><span>case</span> 8:
<span>return</span> '良好'<span>;
</span><span>case</span> 7:
<span>return</span> '好'<span>;
</span><span>case</span> 6:
<span>return</span> '可以'<span>;
</span><span>default</span>:
<span>return</span> '差'<span>;
}
}
</span><span>echo</span> getLevel_switch(60).'<br/>';- 控制语句写法3
<span>function</span> getLevel_break(<span>$score</span><span>){
</span><span>$result</span> = '--'<span>;
</span><span>switch</span>(<span>intval</span>(<span>$score</span>/10<span>)){
</span><span>case</span> 10:
<span>case</span> 9:
<span>$result</span> = '优秀';<span>break</span><span>;
</span><span>case</span> 8:
<span>$result</span> = '良好';<span>break</span><span>;
</span><span>case</span> 7:
<span>$result</span> = '好';<span>break</span><span>;
</span><span>case</span> 6:
<span>$result</span> = '可以';<span>break</span><span>;
}
</span><span>return</span> <span>$result</span><span>;
}
</span><span>echo</span> getLevel_break(83).'<br/>';
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4.循环- for循环
<span>for</span>(<span>$i</span>=0;<span>$i</span><100;<span>$i</span>++<span>){
</span><span>echo</span> 'Hello '.<span>$i</span>.'<br/>'<span>;
}</span>- while循环 先判断再执行
<span>$i</span> = 0<span>;
</span><span>while</span>(<span>$i</span> < 50<span>){
</span><span>echo</span> 'Hello '.<span>$i</span>.'<br/>'<span>;
</span><span>$i</span>++<span>;
}</span>- do-while循环 先执行在判断
<span>$i</span> = 0<span>;
</span><span>do</span><span>{
</span><span>echo</span> 'Hello '.<span>$i</span>.'<br>'<span>;
</span><span>$i</span>++; <span>//</span><span>一定不要忘记自增，否则就会编程死循环</span>
}<span>while</span>(<span>$i</span><20);- break跳出 *整个* 循环
<span>for</span>(<span>$i</span>=0;<span>$i</span><100;<span>$i</span>++<span>){
</span><span>echo</span> 'Hello '.<span>$i</span>.'<br/>'<span>;
</span><span>if</span>( <span>$i</span> == 20<span> ){
</span><span>break</span><span>;
}
}</span>- continue 跳出 *本次* 循环
<span>for</span>(<span>$i</span>=0;<span>$i</span><100;<span>$i</span>++<span>){
</span><span>echo</span> 'Hello '.<span>$i</span>.'<br/>'<span>;
</span><span>//</span><span> if( $i == 20 ){
// break;
// }</span>
<span>if</span>(20 == <span>$i</span><span>){
</span><span>continue</span><span>;
}
</span><span>echo</span> 'Run here '.<span>$i</span>.'<br/>'<span>;
}</span>
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5.逻辑运算 与&& 或|| 非!<span>function</span><span> traceNum(){
</span><span>for</span>(<span>$i</span>=0;<span>$i</span><=100;<span>$i</span>++<span>){
</span><span>//</span><span> if(0 == $i%2 && 0==$i%3){
// echo $i.'<br/>';
// }
// if(0 == $i%2 || 0==$i%3){
// echo $i.'<br/>';
// }</span>
<span>if</span>(!(0 == <span>$i</span>%2<span>)){
</span><span>echo</span> <span>$i</span>.'<br/>'<span>;
}
}
}
traceNum();</span>
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