A String insertion
The difference between a double quote and a single quote:
1. Use of double quotes:
Copy CodeThe code is as follows:
Double quotation marks can parse variables and escape characters
$username = "Jack";
echo "His name is $username!";
echo "
";
$username = "small East";
If the exclamation point in English will parse the variable normally
echo "His name is $username!"; /His name is little East!
echo "
";
If it is Chinese exclamation point will not parse out
echo "His name is $username!. ";//His name is
echo "
";
The escape character is parsed here, but \ nthe line is wrapped in the source code.
The browser displays the location of just one character
echo "His name is $username,\n he is 20 years old this year";//His name is Xiao Dong, he is 20 years old this year.
echo "
";
To avoid errors, it is recommended to use the string connection method
echo "His name is". $username. "He's 20 years old this year";//His name is Xiao Dong, he's 20 years old this year.
?>
2. Use of single quotation marks:
Copy CodeThe code is as follows:
Single quotes are just output string literals,
Variables and escape characters are not parsed.
Also does not prompt for syntax highlighting
$username = ' Anllin ';
Echo ' His name is $username, \ n is 20. ';
Output
His name is $username, \ n his is 20.
?>
Some of the commonly used escape characters
Escape sequences |
Describe |
\ n |
Line break |
\ r |
Enter |
\ t |
Horizontal chart |
\\ |
Back slash |
\$ |
Dollar symbol |
\” |
Double quotes |
two. Operator
Copy CodeThe code is as follows:
Arithmetic operators
$a = 5;
$b = 3;
echo $a + $b;
Echo '
';
echo $a-$b;
Echo '
';
Echo $a * $b;
Echo '
';
echo $a/$b;
Echo '
';
echo $a% $b;
?>
8
2
15
1.66666666667
2
Copy CodeThe code is as follows:
Compound assignment operator
$a = 5;
$b = 3;
echo $a + = $b;
Echo '
';
echo $a-= $b;
Echo '
';
echo $a *= $b;
Echo '
';
echo $a/= $b;
Echo '
';
echo $a%= $b;
Echo '
';
echo $a. = $b;
?>
8
5
15
5
2
23
Copy CodeThe code is as follows:
Increment decrement operator
$a = 5;
echo + + $a;
Echo '
';
echo $a + +;
Echo '
';
echo--$a;
Echo '
';
echo $a--;
?>
6
6
6
6
Copy CodeThe code is as follows:
$a = 5;
$b = 3;
$c = 5;
$d = ' 5 ';
echo $a = = $c;
Echo '
';
echo $a = = = $c;
Echo '
';
echo $a = = $d;
Echo '
';
echo $a! = $b;
Echo '
';
echo $a!== $d;
Echo '
';
echo $a! = $b;
Echo '
';
echo $a > $b;
Echo '
';
echo $b < $c;
Echo '
';
echo $a >= $c;
Echo '
';
echo $a <= $c;
?>
1
1
1
1
1
1
1
1
1
1
Copy CodeThe code is as follows:
$a = false;
Echo! $a;
Echo '
';
$b = 5;
$c = 3;
echo $b > 0 && $c > 0;
Echo '
';
echo $b > 0 and $c > 0;
Echo '
';
echo $b! = 0 | | $c! = 0;
Echo '
';
echo $b! = 0 or $c! = 0;
Echo '
';
?>
1
1
1
1
1
Operator "and" and "or" than && and | | The priority level is lower
Ternary operator
Copy CodeThe code is as follows:
$a = 100;
echo $a > 60? ' Success ': ' Fail ';
?>
Success
Error suppression operator
Copy CodeThe code is as follows:
echo @ (100/0);
?>
Three Control structure
If condition judgment statement
Copy CodeThe code is as follows:
$a = 10;
if ($a > 0)
{
echo ' integer greater than 0 ';
}
Echo '
';
if ($a > 0)
{
echo ' integer greater than 0 ';
}
else if ($a < 0)
{
echo ' integer less than 0 ';
}
Else
{
echo ' integer equals zero ';
}
?>
Switch statement
Copy CodeThe code is as follows:
$role = ' admin ';
Switch ($role)
{
Case ' admin ':
echo ' admin ';
Break
Case ' user ':
Echo ' Ordinary user ';
Break
Case ' guest ':
Echo ' Visitor ';
Break
Default:
Echo ' Visitor ';
Break
}
?>
While Loop statement
Copy CodeThe code is as follows:
$a = 10;
while ($a > 0)
{
echo $a--;
Echo '
';
}
?>
Do and loop statements
Copy CodeThe code is as follows:
$a = 10;
Do
{
echo $a--;
Echo '
';
}
while ($a > 0)
?>
For Loop statement
Copy CodeThe code is as follows:
for ($a = 0; $a < $a + +)
{
echo $a;
Echo '
';
}
?>
Break statement
Copy CodeThe code is as follows:
for ($a = 0; $a < $a + +)
{
echo $a;
Echo '
';
if ($a ==5)
{
break;//terminates the loop, but executes the statement following the loop
}
}
echo ' Loop over ';
?>
Exit statement
Copy CodeThe code is as follows:
for ($a = 0; $a < $a + +)
{
echo $a;
Echo '
';
if ($a ==5)
{
exit;//exit directly, the statement behind the loop does not execute
}
}
echo ' Loop over ';
?>
Continue statements
Copy CodeThe code is as follows:
for ($a = 0; $a < $a + +)
{
echo $a;
Echo '
';
if ($a ==5)
{
continue;//end this cycle, continue the next loop, the statement after the loop still executes
}
}
echo ' Loop over ';
?>
http://www.bkjia.com/PHPjc/324812.html www.bkjia.com true http://www.bkjia.com/PHPjc/324812.html techarticle A. The difference between a string and a single quotation mark: 1. Use of double quotes: copy code as follows: Meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "? PHP//double ...
