What is the significance of the error message "Deprecated: Function eregi() is deprecated in PHP" and how does it affect PHP code?

The error message "Deprecated: Function eregi() is deprecated in PHP" indicates that the eregi() function is no longer supported in PHP and should not be used in the code. To resolve this issue, you should replace eregi() with the preg_match() function, which provides similar functionality but is the recommended method for pattern matching in PHP.

// Before
if (eregi('pattern', $string)) {
    // do something
}

// After
if (preg_match('/pattern/i', $string)) {
    // do something
}