The class itself is abstract. Two subclasses,
QDoubleValidator, provide basic numeric-range checking, and
QRegExpValidatorprovides general checking using a custom regular expression.
validate()must be implemented by every subclass. It returns
Acceptabledepending on whether its argument is valid (for the subclass’s definition of valid).
These three states require some explanation. An
Invalidstring is clearly invalid.
Intermediateis less obvious: the concept of validity is difficult to apply when the string is incomplete (still being edited).
Intermediateas the property of a string that is neither clearly invalid nor acceptable as a final result.
Acceptablemeans that the string is acceptable as a final result. One might say that any string that is a plausible intermediate state during entry of an
Here are some examples:
For a line edit that accepts integers from 10 to 1000 inclusive, 42 and 123 are
Acceptable, the empty string and 5 are
Intermediate, and “asdf” and 1114 is
For an editable combobox that accepts URLs, any well-formed URL is
Acceptable, “http://example.com/,” is
Intermediate(it might be a cut and paste action that accidentally took in a comma at the end), the empty string is
Intermediate(the user might select and delete all of the text in preparation for entering a new URL) and “http:///./” is
For a spin box that accepts lengths, “11cm” and “1in” are
Acceptable, “11” and the empty string are
Intermediate, and “http://example.com” and “hour” are
fixup()is provided for validators that can repair some user errors. The default implementation does nothing.
QLineEdit, for example, will call
fixup()if the user presses Enter (or Return) and the content is not currently valid. This allows the
fixup()function the opportunity of performing some magic to make an
A validator has a locale, set with
setLocale(). It is typically used to parse localized data. For example,
QDoubleValidatoruse it to parse localized representations of integers and doubles.
- param parent
Sets up the validator. The
parentparameter is passed on to the
This enum type defines the states in which a validated string can exist.
The string is clearly invalid.
The string is a plausible intermediate value.
The string is acceptable as a final result; i.e. it is valid.
arg__1 – unicode
This function attempts to change
inputto be valid according to this validator’s rules. It need not result in a valid string: callers of this function must re-test afterwards; the default does nothing.
Reimplementations of this function can change
inputeven if they do not produce a valid string. For example, an ISBN validator might want to delete every character except digits and “-“, even if the result is still not a valid ISBN; a surname validator might want to remove whitespace from the start and end of the string, even if the resulting string is not in the list of accepted surnames.
- Return type
Returns the locale for the validator. The locale is by default initialized to the same as QLocale().
localethat will be used for the validator. Unless has been called, the validator will use the default locale set with
setDefault(). If a default locale has not been set, it is the operating system’s locale.
arg__1 – unicode
- Return type
This virtual function returns
inputis invalid according to this validator’s rules,
Intermediateif it is likely that a little more editing will make the input acceptable (e.g. the user types “4” into a widget which accepts integers between 10 and 99), and
Acceptableif the input is valid.
The function can change both
pos(the cursor position) if required.
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