分支结构

if 语句

$a = 1;
$b = 2;
if($a > $b) {
    echo "a大于b";
}

if($a > $b) {
    echo "a大于b";
} else {
    echo "a小于b";
}

if($a > $b) {
    echo "a大于b";
} elseif( $a < $b) {
    echo "a小于b";
} else {
    echo "a等于b";
}

$hour = 11;
if($hour < 10) {
    echo "早上好";
} elseif( $a < 13) {
    echo "中午好";
} elseif( $a < 18) {
    echo "下午好";
} else {
    echo "晚上好";
}

switch 语句

$week = date("D");
switch($week) {
    case "Mon":
        echo "星期一";
 ...