The error_reporting() function sets the error_reporting directive at runtime. PHP has many levels of errors, using this function sets that level for the duration (runtime) of your script.
error_reporting() sets PHP's error reporting level, and returns the old level. The level parameter takes on either a bitmask, or named constants. Using named constants is strongly encouraged to ensure compatibility for future versions. As error levels are added, the range of integers increases, so older integer-based error levels will not always behave as expected.
Example 1. error_reporting() examples
The available error level constants are listed below. The actual meanings of these error levels are described in the predefined constants.
Table 1. error_reporting() level constants and bit values
With PHP > 5.0.0 E_STRICT with value 2048 is available. E_ALL does NOT include error level E_STRICT.