How to bind QString value in perticular range ?

[Qt embedded developer]

i want to do operation on string which has value between "000" to "999".

NOW when unknown string come at that time i need to replace it with "000".

Is anybody know how to implement this logic ?

my code is written below. there is instead "c" and "". any string can come.

QString sCurrentFuelGaugeFirmwareValue = receive();

if(sCurrentFuelGaugeFirmwareValue == "v" || sCurrentFuelGaugeFirmwareValue == "")
sCurrentFuelGaugeFirmwareValue = "000";
if(sNewFuelGaugeFirmwareValue == "")
sNewFuelGaugeFirmwareValue = "000";

[JonB]

@JKSH

It doesn't fully work. "1111" >= "000" and "1111" <= "999" are both true.

Again I'm not with you. That is a 4-digit string. Just like my 0001 example above. I stated that would be treated as acceptable, where the OP might want unacceptable. I said my suggestion is "lazy" because of this, it works assuming the input is 3 characters long.

Equally @TheGringerEye's solution treats, say, a 2-digit 12 as valid, we don't know what the OP wants done with that. These solutions depend on precisely what the OP wants treated how....

If the OP wants the "lazy" way it could be improved with

if (! (str.length() == 3 && str >= "000" && str <= "999"))
    str = "000";

EDIT MY BAD, NOT ENOUGH COFFEE YET, I CORRECT MYSELF IN LATER POST....

[JonB]

@Qt-embedded-developer said in How to bind QString value in perticular range ?:

i want to do operation on string which has value between "000" to "999".
NOW when unknown string come at that time i need to replace it with "000".

A "lazy" way would be

if (! (str >= "000" && str <= "999"))
    str = "000";

EDIT MY BAD, NOT ENOUGH COFFEE YET, I CORRECT MYSELF IN LATER POST....

A more robust way would be to use QRegularExpression.

[J.Hilk]

@JonB said in How to bind QString value in perticular range ?:

if (! (str >= "000" && str <= "999"))
str = "000";

I'm disgusted, that this actually works, feels like Python/JavaScript

I wonder how the >= is actually implemented 🤔

[JonB]

@J-Hilk
Well I never test anything, I just type in my proposed answers.

I'm lost, why disgusted? What do you mean about "how >= is implemented"? It's a straight string comparison, and digits are guaranteed to be consecutive characters or code points or whatever they call them. It's not going to convert to the number, if that's what you mean.

Just to be clear, if the input were, say, 0001 this test would treat that as valid, and not alter to 000, which a regular expression could correctly catch. But if the OP knows the input is always 3 characters it suffices. Of course I would use the reg ex, but the OP might not fancy that....

[TheGringerEye]

QString test("63");
QIntValidator valid(0, 999);
int pos;
if (QValidator::State::Acceptable != valid.validate(test, pos))
{
    test = QLatin1Char('0');
}
test = test.sprintf("%03i", test.toInt());

[JKSH]

@J-Hilk said in How to bind QString value in perticular range ?:

I'm disgusted, that this actually works, feels like Python/JavaScript

It doesn't fully work. "1111" >= "000" and "1111" <= "999" are both true.

[Qt embedded developer]

@TheGringerEye it gives below error
error: 'QValidator::State' is not a class or namespace
if (QValidator::State::Acceptable != valid.validate(test, pos))
^

[TheGringerEye]

@Qt-embedded-developer
#include <QIntValidator>

[J.Hilk]

@JonB Well, that would make a bit more sense, true

TBH I expected this to default to a length comparison or pointer/addresses

Don't mind me, I'm way behind on my daily coffee doses

[JonB]

@JKSH

It doesn't fully work. "1111" >= "000" and "1111" <= "999" are both true.

Again I'm not with you. That is a 4-digit string. Just like my 0001 example above. I stated that would be treated as acceptable, where the OP might want unacceptable. I said my suggestion is "lazy" because of this, it works assuming the input is 3 characters long.

Equally @TheGringerEye's solution treats, say, a 2-digit 12 as valid, we don't know what the OP wants done with that. These solutions depend on precisely what the OP wants treated how....

If the OP wants the "lazy" way it could be improved with

if (! (str.length() == 3 && str >= "000" && str <= "999"))
    str = "000";

EDIT MY BAD, NOT ENOUGH COFFEE YET, I CORRECT MYSELF IN LATER POST....

[TheGringerEye]

@JonB Yes, if you need not to skip "0001", then you need to add a check for the length of the string

[JonB]

EDIT MY BAD, NOT ENOUGH COFFEE YET, I CORRECT MYSELF, SORRY....

Sorry, not thinking clearly at all.

If input can contain non-digits, my "lazy":

str >= "000" && str <= "999"

would not be right at all, 0AZ would be acceptable!

So either convert to a number and compare numerically (e.g. QIntValidator or other) or do a regular expression, depending on what is wanted/not wanted....

[Qt embedded developer]

@TheGringerEye said in How to bind QString value in perticular range ?:

#include <QIntValidator>

after adding header file still i get error QValidator::State is not a class or name space

[jsulm]

@Qt-embedded-developer It should be

if (QValidator::Acceptable != valid.validate(test, pos))

Easy to find out actually by reading documentation and considering how C++ enums work...