if Judgment statement
Format: if (condition){
Execution code
}
<?php
header("Content-type: text/html; charset=utf-8");//设置编码
$a = 15;
if($a==15){
echo "满足条件";
}
//注：条件判断的时候，不要写一个等号 一个等号是赋值
?> if...else Statement
Format if (condition){
Code block 1;
}else{
Code Block 2;
}
<?php
header("Content-type: text/html; charset=utf-8");//设置编码
//if....else
//1代表 北京 0代表上海
$i=0;
if($i==1){
echo "欢迎来到北京";
}else{
echo "欢迎来到上海";
}
?>Note: Give a variable and assign a value equal to 0 Determine whether $i is equal to 1 If equal, output the first echo statement, otherwise output the second echo statement
if...else if...else
Format: if (condition 1){
Code block 1;
}else if(condition 2){
Code block 2;
}else{
Code block 3;
}
<?php
header("Content-type: text/html; charset=utf-8");//设置编码
//判断一个人的考试成绩
//60以下不及格
//70-80之间良好
//80-90之间非很好
//90-100之间优秀
$a = 90;
if($a<60){
echo "不及格";
}else if($a>=60 and $a<80){
echo "良好";
}else if($a>=80 and $a<90){
echo "非常好";
}else{
echo "优秀";
}
?>
##switch statement
Format:
$a = 2;
switch($a){
case 1: Execute code 1; break;
case 2: execute code 2; break;
case 3: execute code 3; break;
case 4: execute code 4; break;
default: execute code;
}
<?php
header("Content-type: text/html; charset=utf-8");//设置编码
//判断一个人是年纪大小的状况
$a = 50;
switch ($a) {
case 20:echo "少年";break;
case 30:echo "青年";break;
case 40:echo "中年";break;
case 50:echo "中老年";break;
default:echo "老年";
}
?>
break jump
In switch, when the break statement is encountered, Instead of executing downward, realize the jump
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