Php coding with output

# Outputting the Value of a Variable

To build a dynamic and interactive PHP program, it is useful to output variables and their values. The PHP language allows for multiple methods of value output. This topic covers the standard methods of printing a value in PHP and where these methods can be used.

# echo and print

(opens new window) are language constructs, not functions. This means that they don’t require parentheses around the argument like a function does (although one can always add parentheses around almost any PHP expression and thus echo(«test») won’t do any harm either). They output the string representation of a variable, constant, or expression. They can’t be used to print arrays or objects.

echo $name; #> Joel print $name; #> Joel 

echo($name); #> Joel print($name); #> Joel 

echo $name, "Smith"; #> JoelSmith echo($name, " ", "Smith"); #> Joel Smith 

# Shorthand notation for echo

(opens new window) , a shorthand notation for echo is available by default, using to end it. For example:

p>$variable?>p> p> "This is also PHP" ?>p> 

Note that there is no terminating ; . This works because the closing PHP tag acts as the terminator for the single statement. So, it is conventional to omit the semicolon in this shorthand notation.

# Priority of print

Although the print is language construction it has priority like operator. It places between = += -= *= **= /= .= %= &= and and operators and has left association. Example:

echo '1' . print '2' + 3; //output 511 

Same example with brackets:

echo '1' . print ('2' + 3); //output 511 

# Differences between echo and print

In short, there are two main differences:

• print only takes one parameter, while echo can have multiple parameters.
• print returns a value, so can be used as an expression.

# Outputting a structured view of arrays and objects

# print_r()

(opens new window) — Outputting Arrays and Objects for debugging

(opens new window) will output a human readable format of an array or object.

You may have a variable that is an array or object. Trying to output it with an echo will throw the error:
Notice: Array to string conversion . You can instead use the print_r function to dump a human readable format of this variable.

You can pass true as the second parameter to return the content as a string.

$myobject = new stdClass(); $myobject->myvalue = 'Hello World'; $myarray = [ "Hello", "World" ]; $mystring = "Hello World"; $myint = 42; // Using print_r we can view the data the array holds. print_r($myobject); print_r($myarray); print_r($mystring); print_r($myint); 

This outputs the following:

stdClass Object ( [myvalue] => Hello World ) Array ( [0] => Hello [1] => World ) Hello World 42 

Further, the output from print_r can be captured as a string, rather than simply echoed. For instance, the following code will dump the formatted version of $myarray into a new variable:

$formatted_array = print_r($myarray, true); 

Note that if you are viewing the output of PHP in a browser, and it is interpreted as HTML, then the line breaks will not be shown and the output will be much less legible unless you do something like

echo '
' . print_r($myarray, true) . '
 
'; 
 
Opening the source code of a page will also format your variable in the same way without the use of the tag.
 
Alternatively you can tell the browser that what you’re outputting is plain text, and not HTML:
 
header('Content-Type: text/plain; charset=utf-8'); print_r($myarray); 
 
# var_dump()
 
(opens new window) — Output human-readable debugging information about content of the argument(s) including its type and value 
 
The output is more detailed as compared
 
(opens new window) to print_r because it also outputs the type of the variable along with its value and other information like object IDs, array sizes, string lengths, reference markers, etc.
 
(opens new window) to output a more detailed version for debugging.
 
var_dump($myobject, $myarray, $mystring, $myint); 
 
object(stdClass)#12 (1) ["myvalue"]=> string(11) "Hello World" > array(2)  [0]=> string(5) "Hello" [1]=> string(5) "World" > string(11) "Hello World" int(42) 
 
Note: If you are using xDebug in your development environment, the output of var_dump is limited / truncated by default. See the official documentation
 
(opens new window) for more info about the options to change this.
 
# var_export()
 
(opens new window) dumps a PHP parseable representation of the item.
 
You can pass true as the second parameter to return the contents into a variable.
 
var_export($myarray); var_export($mystring); var_export($myint); 
 
array ( 0 => 'Hello', 1 => 'World', ) 'Hello World' 42 
 
To put the content into a variable, you can do this:
 
$array_export = var_export($myarray, true); $string_export = var_export($mystring, true); $int_export = var_export($myint, 1); // any `Truthy` value 
 
After that, you can output it like this:
 
printf('$myarray = %s; %s', $array_export, PHP_EOL); printf('$mystring = %s; %s', $string_export, PHP_EOL); printf('$myint = %s; %s', $int_export, PHP_EOL); 
 
This will produce the following output:
 
$myarray = array ( 0 => 'Hello', 1 => 'World', ); $mystring = 'Hello World'; $myint = 42; 
 
# String concatenation with echo
 
(opens new window) «end to end» while outputting them (with echo or print for example).
 
You can concatenate variables using a . (period/dot).
 
// String variable $name = 'Joel'; // Concatenate multiple strings (3 in this example) into one and echo it once done. // 1. ↓ 2. ↓ 3. ↓ - Three Individual string items echo '
Hello ' . $name . ', Nice to see you.
'; // ↑ ↑ - Concatenation Operators #> "
Hello Joel, Nice to see you.
" 
 
Similar to concatenation, echo (when used without parentheses) can be used to combine strings and variables together (along with other arbitrary expressions) using a comma (,).
 
$itemCount = 1; echo 'You have ordered ', $itemCount, ' item', $itemCount === 1 ? '' : 's'; // ↑ ↑ ↑ - Note the commas #> "You have ordered 1 item" 
 
# String concatenation vs passing multiple arguments to echo
 
Passing multiple arguments to the echo command is more advantageous than string concatenation in some circumstances. The arguments are written to the output in the same order as they are passed in.
 
The problem with the concatenation is that the period . takes precedence in the expression. If concatenated, the above expression needs extra parentheses for the correct behavior. The precedence of the period affects ternary operators too.
 
# printf vs sprintf
 
(opens new window) will output a formatted string using placeholders
 
(opens new window) will return the formatted string
 
$name = 'Jeff'; // The `%s` tells PHP to expect a string // ↓ `%s` is replaced by ↓ printf("Hello %s, How's it going?", $name); #> Hello Jeff, How's it going? // Instead of outputting it directly, place it into a variable ($greeting) $greeting = sprintf("Hello %s, How's it going?", $name); echo $greeting; #> Hello Jeff, How's it going? 
 
It is also possible to format a number with these 2 functions. This can be used to format a decimal value used to represent money so that it always has 2 decimal digits.
 
$money = 25.2; printf('%01.2f', $money); #> 25.20 
 
(opens new window) , but accept a format string and an array of values, instead of individual variables.
 
# Outputting large integers
 
On 32-bits systems, integers larger than PHP_INT_MAX are automatically converted to float. Outputting these as integer values (i.e. non-scientific notation) can be done with printf , using the float representation, as illustrated below:
 
foreach ([1, 2, 3, 4, 5, 6, 9, 12] as $p)  $i = pow(1024, $p); printf("pow(1024, %d) > (%7s) %20s %38.0F", $p, gettype($i), $i, $i); echo " ", $i, "\n"; > // outputs: pow(1024, 1) integer 1024 1024 1024 pow(1024, 2) integer 1048576 1048576 1048576 pow(1024, 3) integer 1073741824 1073741824 1073741824 pow(1024, 4) double 1099511627776 1099511627776 1099511627776 pow(1024, 5) double 1.1258999068426E+15 1125899906842624 1.1258999068426E+15 pow(1024, 6) double 1.1529215046068E+18 1152921504606846976 1.1529215046068E+18 pow(1024, 9) double 1.2379400392854E+27 1237940039285380274899124224 1.2379400392854E+27 pow(1024, 12) double 1.3292279957849E+36 1329227995784915872903807060280344576 1.3292279957849E+36 
 
Note: watch out for float precision, which is not infinite!
 
While this looks nice, in this contrived example the numbers can all be represented as a binary number since they are all powers of 1024 (and thus 2). See for example:
 
$n = pow(10, 27); printf("%s %.0F\n", $n, $n); // 1.0E+27 1000000000000000013287555072 
 
# Output a Multidimensional Array with index and value and print into the table
 
Array ( [0] => Array ( [id] => 13 [category_id] => 7 [name] => Leaving Of Liverpool [description] => Leaving Of Liverpool [price] => 1.00 [virtual] => 1 [active] => 1 [sort_order] => 13 [created] => 2007-06-24 14:08:03 [modified] => 2007-06-24 14:08:03 [image] => NONE ) [1] => Array ( [id] => 16 [category_id] => 7 [name] => Yellow Submarine [description] => Yellow Submarine [price] => 1.00 [virtual] => 1 [active] => 1 [sort_order] => 16 [created] => 2007-06-24 14:10:02 [modified] => 2007-06-24 14:10:02 [image] => NONE ) ) 
 
Output Multidimensional Array with index and value in table
 
table>  foreach ($products as $key => $value)  foreach ($value as $k => $v)  echo ""; echo "$k"; // Get index. echo "$v"; // Get value. echo ""; > > ?> table> 
 
# Remarks
 
Variables in PHP come in a variety of types. Depending on the use case, you may want to output them to the browser as rendered HTML, output them for debugging, or output them to the terminal (if running an application via the command line).
 
Below are some of the most commonly used methods and language constructs to output variables:
 
Note: When trying to output an object as a string, PHP will try to convert it into a string (by calling __toString()
 
(opens new window) — if the object has such a method). If unavailable, an error similar to Object of class [CLASS] could not be converted to string will be shown. In this case, you’ll have to inspect the object further, see: outputting-a-structured-view-of-arrays-and-objects
 
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PHP echo and print Statements
 
With PHP, there are two basic ways to get output: echo and print .
 
In this tutorial we use echo or print in almost every example. So, this chapter contains a little more info about those two output statements.
 
PHP echo and print Statements
 
echo and print are more or less the same. They are both used to output data to the screen.
 
The differences are small: echo has no return value while print has a return value of 1 so it can be used in expressions. echo can take multiple parameters (although such usage is rare) while print can take one argument. echo is marginally faster than print .
 
The PHP echo Statement
 
The echo statement can be used with or without parentheses: echo or echo() .
 
Display Text
 
The following example shows how to output text with the echo command (notice that the text can contain HTML markup):
 
Example
 
echo «
 
PHP is Fun!
 
«; 
echo «Hello world!
«;
echo «I’m about to learn PHP!
«; 
echo «This «, «string «, «was «, «made «, «with multiple parameters.»; 
?> 
Display Variables
 
The following example shows how to output text and variables with the echo statement:
 
Example
 
echo «
 
» . $txt1 . «
 
«;
echo «Study PHP at » . $txt2 . «
«;
echo $x + $y;
?>
 
The PHP print Statement
 
The print statement can be used with or without parentheses: print or print() .
 
Display Text
 
The following example shows how to output text with the print command (notice that the text can contain HTML markup):
 
Example
 
print «
 
PHP is Fun!
 
«; 
print «Hello world!
«;
print «I’m about to learn PHP!»; 
?> 
Display Variables
 
The following example shows how to output text and variables with the print statement:
 
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