PHP Learning Process Control implementation code

The code is as follows:

<?php/* * Process Control * * One, sequential structure * Two, branch structure--Conditional structure--Select structure * 1. Single Branch *//condition bool,true or false,> < = = | | | ! * IF (condition) * Executes the following statement * if (condition) * {* code snippet; * Code snippet; *} * * 2. Dual Branch * Use ELSE clause * * IF (condition) * Execute a statement * else * Execute a statement * if (condition) {*  Bar or multiple code *}else{* One or more codes *} * 3. Multi-Branch * can use if else if and switch case *//This is a mutually exclusive relationship * if (condition) {* * *}else if (condition) {*}else if (condition) {*}else{*} * 4. Nested branch * if () {* if () {*}else{* if () {} *} *} * Three, loop structure * * * * * * * Summary: * If you are judging a range then use the ElseIf * If it is a single match, use the switch case *////single-path execution $a = 10; $b = 5; if ($a > $b) echo "$a is greater than $b"; Two-way execution $a = 10; $b = 20; if ($a > $b) {echo "$a greater than $b </br>";} else {echo "$a less than $b </br>";}//Multi-route execution $hour =date ("H"); if ($hour > 6 && $hour < 9) {echo "Good morning!":} else if ($hour > 9 && $hour <) {echo] Good Morning "; } else if ($hour > && $hour <) {echo "Good noon";} else if ($hour > && $hour <) {echo] Good afternoon "; } else if ($hour > && $hour <) {echo "Good evening""; } else if ($hour > && $hour <22) {echo "Good evening"} else {echo "Good Night"}//improved code based on mutex $hour =date ("H"); if ($hour < 9) {echo "Good morning!":} else if ($hour <) {echo "Good Morning";} else if ($hour <) {echo case "Mon ": Echo" Monday "; break; " Good noon "; } else if ($hour <) {echo "Good afternoon"} else if ($hour >) {echo "Good evening";} else if ($hour <) {echo "Good Evening"} Els e {echo "Good Night"}//Judgment Day of the week $week =date ("D");//Get Days of the week switch ($week)//switch (variable) variable only with integer and string {case "Mon": echo "Monday"; Case "Tue" echo "Tuesday"; Break Case "Wed": echo "Wednesday"; Break Case "Thu": echo "Thursday"; Break Case "Fri": echo "Friday"; Break Default:echo "Weekend"; }//Nested class $sex =$_get["sex"]; $age =$_get["age"]; if ($sex = = "Nan") {if ($age >=) {echo "This $sex has retired". $age-60). " Years "; } else {echo "This man is still working, and". ( 60-$age). " Years of retirement "; }} else {if ($age >=) {echo "This $sex has retired". $age-66). " Years "; } else {echo "This lady is still working, and". ( 66-$age). " Years of retirement "; }}?>

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