PHP basic syntax and data types study notes_PHP tutorial

An entry-level article on basic PHP syntax and data types. I hope it can provide some help to all PHP beginners.

PHP basic syntax and data types:

(1), PHP basic syntax:

1. Mixed HTML and PHP
                                                                                                                                                                                                                      ​​​​​​​ 3. How to define a variable and how to use it

(2), PHP data operation type

Four scalar types:

                   boolean (Boolean type) understood as true or false type
                        integer (integer type)
Float (floating point type, also called "double") is understood as decimal type
String (string)

Two compound types:

                         array (array)
object

(3) Five operation types of PHP

1. Arithmetic operations

2. Assignment operation (such as: $a=100)

3. Comparison operations (such as: $a<$b)

4. Logical operations (such as: $a&&$b)

5. Increment and decrement operations (such as: $a++)

(4) switch conditional statement

switch conditional statement

$i=1;

switch($i){

case 0;
echo "The value of i is 0";
          break;
case 1;
echo “The value of i is 1″;
          break;
case 2;
              echo “The value of i is 2″;
          break;
Default: echo "None of the above values";

}

?>

break n jump out of loop statement

break n jump out of n level loop

Example:

for($i=1;$i<=5;$i++){
echo “i=".$i."
";
for($j=1;$j<=5;$j++){
echo “ j=”.$j.”
”;
for($k=1;$k<=5;$k++){
echo “ k=”.$k.”
”;
If($k==2){
         break;
}
            }
if($j==3){
Break 2;
}
}

echo “
”;
}
?>

(5) do while loop

//Execute once before judging

do{
echo “Execution loop”;
$a++;
}while($a>100);//Note there is a semicolon
echo “
”;
//Judge first and then execute

while($a>100){
echo “Execution loop”;
$a++;
}
?>

Functions commonly used in PHP arrays

foreach($arr as $key=>$val){}//Traverse the array

count($arr)//length of statistical array

is_array($arr)//Judge array

explode(“key”,$str)//Split the string into an array

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