PHP Basic Learning Notes

<! DOCTYPE html>

<body>
<?php
echo "Hello world!";
?>
</body>

PHP's Hello world.
After entering the Chinese language after the garbled situation, Baidu is a bit of coding problem, in the PHP code to add the header ("content-type:text/html; Charset=utf-8 "), after the resolution, after I modify the php.ini, find Default_charset to modify the default encoding, after restarting the computer to take effect, now the default encoding becomes Utf-8.

<! DOCTYPE html>

<body>
<?php
echo "Hello world!";
echo "First PHP";
?>
</body>

? Three ways to Annotate://#/**/
? PHP is insensitive to user-defined functions, classes, and keyword sizes. However, the variable name is case sensitive.
? PHP does not need to specify the data type when defining variables, the system will automatically convert. Three scopes: 1.local (local) 2.global (global) 3.static (Static)
PHP also stores all global variables in an array of $globals[index]. The subscript contains the variable name. This array is also accessible within the function and can be used to update global variables directly.
<?php
$x = 5;
$y = 10;
function MyTest () {
$GLOBALS [' y ']= $GLOBALS [' x ']+ $GLOBALS [' Y '];
}
MyTest ();
Echo $y;
?>
After the function finishes executing, all variables are deleted. However, sometimes I need to not delete a local variable.
<?php
function MyTest () {
static $x = 0;
echo $x;
$x + +;
}
MyTest ();
MyTest ();
MyTest ();
?>
echo vs Print difference: 1.echo-can output more than one string 2.print-can only output one string and always return 1
Echo is slightly faster than print, thinking he doesn't have to return any values.
<?php
echo "echo "Hello world<br>";
echo "I ' m about to learn php!<br>";
echo "This", "string", "is", "made", "with multiple parameters (many parameters)";
?>
Display variables:
<?php
$txt 1= "Learn PHP";
$txt 2= "W3School.com.cn";
$cars =array ("Volvo", "BMW", "SAAB");

echo $txt 1. " <br> ";//use. And, to concatenate strings
echo "Study PHP at $txt 2 <br>";
echo "My car is a $cars [0]";
?>
The print statement is the same as above, but the difference is that you cannot use it to connect, but you can use it. The connection is counted as a string.
<?php
$txt 1= "Learn PHP";
$x =print $txt 1. " 112233 "." SSS "." <br> ";
Print $x;
?>
The Var_dump () method is to determine the type and length of a variable, and to output the value of a variable if the variable has a value for the output of the variable and returns the data type.
PHP String Functions
1.strlen () returns the string length echo strlen ("Hello world!");
2.strpos () is used to retrieve characters or text within a string, and returns a character position if found, or false if not found.
Constants: Constants are preceded by a $ symbol, and are automatically global. Three parameters for define ():
1. Name of the first parameter definition constant
2. The second parameter defines the value of a constant
3. The optional third parameter specifies whether the constant name is case-sensitive. The default is False (sensitive).
Define ("abc", "dddd");
ECHO ABC;
Operator:/floating-point division,% modulo.
= = Equals (same value) = = = Congruent (same type, same order in array)!== not congruent (completely different)
foreach applies only to array traversal.
<?php
$colors =array ("Red", "green", "blue", "yellow");
foreach ($colors as $value) {
echo "$value <br>";
}
?>
Gets the array length count () function
<?php
$cars =array ("Volvo", "BMW", "SAAB");
echo count ($cars);
?>
An associative array is an array that uses the specified key assigned to the array.
<?php
$age =array ("Bill" = "+", "Steve" = "Notoginseng", "Peter" and "43");
echo "Peter is". $age [' Peter ']. "Years-old.";
?>
Loop with foreach
<?php
$age =array ("Bill" = "+", "Steve" = "Notoginseng", "Peter" and "43");
foreach ($age as $x = = $xage) {
echo $x. "Name is" $xage. "Years old.<br>";
}
?>
Array sort function
Sort ()-sorts an array in ascending order
Rsort ()-sorts the array in descending order
Asort ()-sorts associative arrays in ascending order based on values
Ksort ()-Sorts the associative array in ascending order, based on the key
Arsort ()-sorts associative arrays in descending order by value
Krsort ()-Sorts the associative array in descending order, based on the key
<?php
$cars =array ("Volvo", "BMW", "SAAB");
Sort ($cars);
foreach ($cars as $a) {
echo "$a <br>";
}
?>
<?php
$age =array ("Bill" = "+", "Steve" = "Notoginseng", "Peter" and "43");
Asort ($age);//Sort by value
foreach ($age as $x = + $x _key) {
echo "$x, $x _key<br>";
}
?>

PHP Basic Learning Notes