Table of Contents
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PHP
Install PHP without Apache
PHP docs
O'Reilly PHP cookbook (First Edition, published November 2002)
Debugging PHP
Build in functions
Comparison Operators like !=
Composer, A Dependency Manager for PHP, on Wikipedia. Installation
php-fpm
W3schools tutorial
Wikibooks tutorial
Some more Tutorials and Scripts
XDebug is a PHP extension which provides debugging and profiling capabilities, Wikipedia
Read and write ods files
Run from the command line
--run, -r: Run PHP code without using script tags '<?..?>' php -r 'echo "Hello\n";'
More examples
Run a PHP script
--file, -f: Parse and execute file php -f script.php;
This does not work, presumed --version is a valid option:
php -f script.php --version;
Error:
Error in argument 3, char 2: no argument for option -
Run from a script
#! /usr/bin/php // An (empty) line here results in an (empty) line in the output. <?php // An (empty) line here does not result in an (empty) line in the output. echo "Hello\n"; ?>
Sample PHP web page
<?php echo "Some teskt"; echo "<br>"; echo "Some more tekst"; ?>
Cannnot redeclare
PHP Fatal error: Cannot redeclare a_function() (previously declared in /home/domain/public_html/somefile.php:51) in /home/domains/public_html/somefile.php on line 60
A solution: the file somefile.php is placed in two folders of which one should not contain somefile.php
New line
This works in an offline php script
<?php echo "Hello\n\n\n\n`"; ?>
This does not work in an online php enabled webpage
<?php echo "Some teskt\nSome more tekst"; echo "Some teskt\r\nSome more tekst"; ?>
We did not get the \n nor the \r\n newline to work in an online script. This works
<?php echo "Some teskt"; ?> <br /> <?php echo "Some more tekst"; ?>
You can also use an inline php echo command to get a newline like in
<?php echo "Some teskt"; echo "<br>"; echo "Some more tekst"; ?>
This also works. Make sure the \n has a space before and after it like in the following example
<?php echo nl2br ("Some teskt \n Some more tekst"); ?>
In a Linux terminal running bash
php -r 'echo "Hello" . "\n"; php -r 'echo "Hello\n";'
Special operators
See Tokens on PHP.net
- :: T_PAAMAYIM_NEKUDOTAYIM Scope resolution operator . Also called Paamayim Nekudotayim (Hebrew for double colon)
- -> T_OBJECT_OPERATOR (sometimes called: Member of object)
References
Calculate
/usr/bin/php -r '$tel = 0; $tel++; echo "tel: $tel";'
Colored text
echo "\033[01;31mText in red\033[0m";
for
php -r 'for ($letters = "T"; $letters != "AE"; $letters++) { echo "$letters ";};'
printf
<code php>printf “Percentage sign °”
Debugging
- When an error occurs it is possible that no output shows up, you get a blank screen. Not even the output of the echo commands which you inserted for debugging is shown
- When you run the program and nothing happens start commenting out blocks of code from the end upwards until you get something that runs. Work from there downwards
- Insert code that gives output of variables to get a better idea what is going on. Example: echo nl2br (“\n In file fof_db.php function fof_db_query 1\n”); . The 1 before the \n represents an index number
- See PHP.net for help. Warning: The Description of a command on PHP.net can be confusing / misleading in our experience. What seems obvious is not always obvious
- Install php-xdebug
- Run php -l filename.php
json
Issues
Issue: “Call to undefined function json_decode()“
Do: service php7.3-fpm restart
Issue: “Failed to restart php7.3-fpm.service: Unit php7.3-fpm.service not found.”
Solution: T.b.d.
Errors
Timezone database is corrupt
PHP Fatal error: date(): Timezone database is corrupt - this should *never* happen!
Solution: Check the timezone file in /usr/share/zoneinfo. The permissions should be 644. In our case the UTC file was, for some to us unknown reason, 640
Unexpected end of file
PHP Parse error: syntax error, unexpected end of file, expecting '`' in /home/user/php/hello.php on line 11
Solution: remove the “`” (back tick) somewhere in the program
Call to undefined function
PHP Fatal error: Uncaught Error: Call to undefined function
Solution:
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