Check if wxString Contains Alphabetic Characters Only Topic is solved

[Deluge]

My understanding is that wxString::IsWord() is deprecated, & that I should use the wxRegEx class or the wxString::Matches method. I am not good with regular expressions, but all I want to do is check if a wxString (or wxChar) contains alphabetic characters only.

According to the docs, I should be able to use the "bracket expression" alpha. I thought it would be done like wxString::Matches("[:alpha:]"), but apparently I am mistaken.

Here is the code I am testing with:

Code: Select all

#include <iostream>
#include <wx/string.h>

using namespace std;


bool isAlphaOnly(wxChar c) {
	if (!wxString(c).Matches("[:alpha:]")) return false;
	return true;
}

bool isAlphaOnly(wxString s) {
	cout << "Checking string \"" << s.c_str() << "\":\t";

	for (wxChar c : s) {
		if (!isAlphaOnly(c)) {
			return false;
		}
	}

	return true;
}

string toString(bool b) {
	if (b) return "true";
	else return "false";
}


int main(int argc, char** argv) {
	wxString s1 = "HellowxWidets";
	wxString s2 = "Hello wxWidgets";
	wxString s3 = "HellowxWidgets!";
	wxString s4 = "Hello8wxWidgets";

	cout << "\nAlpha only:\n";
	cout << toString(isAlphaOnly(s1)) << " (should be 'true')\n";
	cout << toString(isAlphaOnly(s2)) << " (should be 'false')\n";
	cout << toString(isAlphaOnly(s3)) << " (should be 'false')\n";
	cout << toString(isAlphaOnly(s4)) << " (should be 'false')\n";

	return 0;
}

If someone could point out my error I would greatly appreciate it. Meanwhile, I will go back to reading the docs.

--- Edit ---

Or maybe bracket expressions only work with the wxRegEx class?

[Deluge]

Found an answer. I can use the expression "^[A-Za-z]+$" with the wxRegEx class (doesn't seem to work with wxString::Matches(_T("^[A-Za-z]+$"))):

Code: Select all

...

const static wxRegEx alpha(_T("^[A-Za-z]+$"));

...

bool isAlphaOnly(wxString s) {
	cout << "Checking string \"" << s.c_str() << "\":\t";

	return alpha.Matches(s);
}

[alys666]

if you need speed, just scan the string with custom function isAlphaChar(..)
regular expressions are slow

Code: Select all

bool isAlphaChar(char fch){
	return (fch >='a'  && fch <='z') || (fch>='A' && fch<='Z');
}

bool isAlphaString(const wxString &fs){
	for(int i=0; i<fs.Length(); ++i){
		if(!isAlphaChar(fs[i])) return false;
	}
	return true;
}

[doublemax]

Beware that all solutions in this thread won't work with Unicode strings. E.g. if the string contains an "ä", the check would be false.

[evstevemd]

If reasons for deprecating IsWord are not affecting your program you can just copy IsWord function from wxWidgets sources as temporary solution.
I don't know why it was deprecated and have no better suggestion!

[Deluge]

Code: Select all

bool isAlphaChar(char fch){
	return (fch >='a'  && fch <='z') || (fch>='A' && fch<='Z');
}

bool isAlphaString(const wxString &fs){
	for(int i=0; i<fs.Length(); ++i){
		if(!isAlphaChar(fs[i])) return false;
	}
	return true;
}

Interesting solution. Thank you.

Beware that all solutions in this thread won't work with Unicode strings. E.g. if the string contains an "ä", the check would be false.

Thank you for the warning doublemax. My program only deals with the basic English alphabet, so I didn't take other Latin symbols into consideration. Wouldn't be hard to make it Unicode compatible with alys666's solution though. Would just need to know the integer values of the characters & extend the formula.

[alys666]

Interesting solution. Thank you.

it's how compilers use to check for alpha string, or identifiers(with added conditions for numbers and '_') .
it will work everywhere, when comparison operation for char type is legal.
unicode is just 16 bit numeric type, and latin alphabet has there the same codes as for ascii. so - no problem