- String
- There are different ways to
quote a
string
in PHP
- The way (= manner) a string is quoted in PHP (and in all "scripting languages") will affect the evaluation of the string....
- There are different ways to
quote a
string
in PHP
- Evaluation:
- Evaluation =
replacing a
variable by
its value
Example:
$x = 5; $x evaluates to: 5
- Evaluation =
replacing a
variable by
its value
- A common practice of
scripting languages:
- Variables can
appear
inside a string
"Hello $a, I'm $b"
- The variables are evaluated differently depending on how the string is quoted !!!
- Variables can
appear
inside a string
- There are
2 ways
to
quote strings
in PHP:
- Single-quote strings:
(no evaluation)
'This is a SINGLE-quoted string'Meaning:
- A single-quote string
is always treated
verbatim
In other words:
- No evaluation takes place inside a single-quote string !!!
Example:
$x = 1 print 'This is a single-quote string. This is $x\n' output: This is a single-quote string. This is $x\nWhat you see in a single-quote string is what you will get !!!
- A single-quote string
is always treated
verbatim
- Double-quote strings:
"This is a DOUBLE-quoted string"Meaning:
- A double-quote string
will perform
evaluation (of variables)
to
construct
the final string
- Exception:
escape character
- The escape character "\" placed before $ will prevent evaluation
Example:
$x = 1 print "This is a single-quote string. This is $x" print "This is a single-quote string. This is \$x" output: This is a single-quote string. This is 1 This is a single-quote string. This is $x - A double-quote string
will perform
evaluation (of variables)
to
construct
the final string
- Single-quote strings:
(no evaluation)
- Example Program:
<?php $x = 1; print 'This is a single-quote string. This is $x\n'; print "This is a double-quote string. This is $x\n"; print "This is a double-quote string. This is \$x\n"; # With escape char ?> Output: This is a single-quote string. This is $x\n (cut line for clarity) This is a double-quote string. This is 1 This is a double-quote string. This is $xHow to run the program:
- ssh -X netid@holland
- php /home/cs377001/PHP/intro-PHP/string1.php