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The QRegExpValidator class is used to check a string against a regular expression. More...
Inherits QValidator.
The QRegExpValidator class is used to check a string against a regular expression.
QRegExpValidator uses a regular expression (regexp) to determine whether an input string is Acceptable, Intermediate, or Invalid. The regexp can either be supplied when the QRegExpValidator is constructed, or at a later time.
When QRegExpValidator determines whether a string is Acceptable or not, the regexp is treated as if it begins with the start of string assertion (^) and ends with the end of string assertion ($); the match is against the entire input string, or from the given position if a start position greater than zero is given.
If a string is a prefix of an Acceptable string, it is considered Intermediate. For example, "" and "A" are Intermediate for the regexp [A-Z][0-9] (whereas "_" would be Invalid).
For a brief introduction to Qt's regexp engine, see QRegExp.
Example of use:
// regexp: optional '-' followed by between 1 and 3 digits
QRegExp rx("-?\\d{1,3}");
QValidator *validator = new QRegExpValidator(rx, this);
QLineEdit *edit = new QLineEdit(this);
edit->setValidator(validator);
Below we present some examples of validators. In practice they would normally be associated with a widget as in the example above.
// integers 1 to 9999 QRegExp rx("[1-9]\\d{0,3}"); // the validator treats the regexp as "^[1-9]\\d{0,3}$" QRegExpValidator v(rx, 0); QString s; int pos = 0; s = "0"; v.validate(s, pos); // returns Invalid s = "12345"; v.validate(s, pos); // returns Invalid s = "1"; v.validate(s, pos); // returns Acceptable rx.setPattern("\\S+"); // one or more non-whitespace characters v.setRegExp(rx); s = "myfile.txt"; v.validate(s, pos); // Returns Acceptable s = "my file.txt"; v.validate(s, pos); // Returns Invalid // A, B or C followed by exactly five digits followed by W, X, Y or Z rx.setPattern("[A-C]\\d{5}[W-Z]"); v.setRegExp(rx); s = "a12345Z"; v.validate(s, pos); // Returns Invalid s = "A12345Z"; v.validate(s, pos); // Returns Acceptable s = "B12"; v.validate(s, pos); // Returns Intermediate // match most 'readme' files rx.setPattern("read\\S?me(\.(txt|asc|1st))?"); rx.setCaseSensitive(false); v.setRegExp(rx); s = "readme"; v.validate(s, pos); // Returns Acceptable s = "README.1ST"; v.validate(s, pos); // Returns Acceptable s = "read me.txt"; v.validate(s, pos); // Returns Invalid s = "readm"; v.validate(s, pos); // Returns Intermediate
See also QRegExp, QIntValidator, QDoubleValidator, and Settings Editor Example.
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