The conditional statements in PHP are if else, switch and ternary operator. Let me introduce to you some syntax of these conditional statements.
Basic syntax structure of if single branch
if(conditional expression){
//Execute statement;
}
if double branch
Basic grammatical structure
if(conditional expression){
//Execute statement;
}else{
//Execute statement;
}
if multiple branches
The basic grammatical structure is
if(conditional expression){
//Execute statement;
}else if (conditional expression){
//Execute statement;
}else if(conditional expression){
//Execute statement;
}else{//There may be more else if
//Execute statement;
}
☞ Please note the above structure:
1) else if can have one or multiple
2) else can be omitted
Example
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if($account == "lord" && $password == "pass"){
echo "欢迎 $_POST[account], 你的密码是 $_POST[password]";
}elseif($_POST[account] == "god" && $_POST[password] == "dog"){
$y = date("Y") - 1911;
$m = date("m");
$d = date("d");
echo "欢迎 $_POST[account], 今天是民国".$y."年".$m."月".$d."日";
}else{
echo "登入失败:
输入的资料:
帐号: $_POST[account]
密码: $_POST[password]";
}
?>
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if($account == "lord" && $password == "pass"){
echo "Welcome $_POST[account], your password is $_POST[password]";
}elseif($_POST[account] == "god" && $_POST[password] == "dog"){
$y = date("Y") - 1911;
$m = date("m");
$d = date("d");
echo "Welcome $_POST[account], today is the Republic of China".$y."Year".$m."Month".$d."Day";
}else{
echo "Login failed:
Input information:
Account: $_POST[account]
Password: $_POST[password]";
}
?>
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switch branch statement
Basic grammatical structure
switch(expression){
case constant 1:
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else {
echo "i is not equal to 0, 1 or 2";
}
?>
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//Execute statement;
break;
case constant 2:
//Execute statement;
break;
defual:
//Execute statement;
break;
}
Example
The following two examples use different methods to achieve the same thing. The first uses if...elseif...else statements, and the other uses switch statements.
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else {<🎜>
echo "i is not equal to 0, 1 or 2";<🎜>
}<🎜>
?>
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The meaning of the above PHP code is: if the variable $i is equal to 0, then output "i equals 0"; if the variable $i is equal to 1, then output "i equals 1"; if the variable $i is equal to 2, then Output "i equals 2"; if neither, output "i is not equal to 0, 1 or 2".
Comparison of switch statement and elseif statement
In a switch statement, the condition is evaluated once and then compared to each case, whereas in an elseif statement, the condition is evaluated again. If your conditions are more complex, or there are multiple loops, it will be faster to use the switch statement.
The code is as follows
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isEmpty="";
$isEmpty=" 非空 ";
$test = empty($isEmpty)?"":trim($isEmpty);
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isEmpty="";
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if (empty($isEmpty)) //条件成立
{
$cookie = "";
}
else
{
$cookie = trim($isEmpty);
}
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$isEmpty=" not empty ";
$test = empty($isEmpty)?"":trim($isEmpty);
Ternary operator?: According to the previous condition empty($isEmpty)true or false, when the condition is true, calculate the expression after ?, and when false, calculate the expression after:.
If you are not used to it, you can change it to the following code
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if (empty($isEmpty)) //Condition is true
{
$cookie = "";
}
else
{
$cookie = trim($isEmpty);
}
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☞ Please note:
1) There are one to many case statements
2) The defaul statement does not need to be included (according to the business logic of your own code)
3) Usually, after the case statement, break is required to indicate exiting the switch statement
4) Type of constant (int, float, string, Boolean)
Supplement
Comparison operators.
$a == $b equals TRUE if $a equals $b.
$a != $b Not equal TRUE if $a is not equal to $b.
$a <> $b does not equal TRUE if $a is not equal to $b.
$a < $b is less than TRUE if $a is strictly less than $b. <🎜>
$a > $b is greater than TRUE if $a is strictly $b.
$a <= $b Less than or equal to TRUE if $a is less than or equal to $b.
$ A & GT; = $ B greater than or equal to True, if $ a is greater than or equal to $ b.
Logical operators.
$ A and $ B and (logic and) true, if $ a and $ B are True.
$ A or $ b or (logic or) true, if $ a or $ b is True.
$a xor
! $a Not (logical NOT) TRUE if $a is not TRUE.
$ A && $ b and (logic and) true, if $ a and $ B are True.
$a || $b Or (logical OR) TRUE if either $a or $b is TRUE.
http://www.bkjia.com/PHPjc/632630.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/632630.htmlTechArticleThe conditional statements in php are if else, switch and ternary operator. Let me introduce these conditions to you. Some syntax of statements. The basic syntax structure of if single branch if (conditional expression) {...
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