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.
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:
echo - Outputs one or more strings
print - Outputs a string and returns
printf - Outputs a formatted string and returns the length of the outputted string
sprintf - Formats a string and returns the formatted string
print_r - Outputs or returns content of the argument as a human-readable string
var_dump - Outputs human-readable debugging information about the content of the argument(s) including its type and value
var_export - Outputs or returns a string rendering of the variable as valid PHP code, which can be used to recreate the value.
Note: When trying to output an object as a string, PHP will try to convert it into a string (by calling
__toString()- if the object has such a method). If unavailable, an error similar to
Object of class [CLASS] could not be converted to stringwill be shown. In this case, you'll have to inspect the object further, see: outputting-a-structured-view-of-arrays-and-objects.