What is the prefix of a QString for QString::toInt(&ok, 2)?

Infinity

I want to convert a QString to an int with QString::toInt() with the following functions:

bool QStringToInt::setIntString(const QString intString)
{
    m_intNumber = 0;

    // The input string is in decimal format
    if (this->stringToInt(intString, 10)) return true;

    // The input string is in hexadecimal format
    if (this->stringToInt(intString, 16)) return true;

    // The input string is in binary format
    if (this->stringToInt(intString, 2)) return true;

    qDebug() << "\n";
    qDebug() << "QStringToInt::setIntString;";
    qDebug().noquote() << "Invalid int string";

    return false;
}

bool QStringToInt::stringToInt(const QString intString, const int base)
{
    bool intStringOk;

    uint intNumber = intString.toUInt(&intStringOk, base);

    if (intStringOk) {
        m_intNumber = intNumber;
        return true;
    } else {
        m_intNumber = 0;
        return false;
    }
}

Which prefix do I have to put in front of the intString that

if (this->stringToInt(intString, 2))

returns true and:

stringToInt(intString, 10)

stringToInt(intString, 16)

return false?

If I put "0x" in front of a string, QString::toInt(&ok, 10) set ok to false and QString::toInt(&ok, 16) sets ok to true. Which is good.

Which prefix do I have to put in front of the string that QString::toInt(&ok, 10) set ok to false, QString::toInt(&ok, 16) sets ok to false and QString::toInt(&ok, 2) sets ok to true?

Chris Kawa

Those ifs in ::setIntString() are wrong. You can't detect the base like that. For example 0 could be binary, octal, decimal, anything from base 1 up really and all those ifs will return true. It just so happens that you treat it as a base 10 first.

QString::toUint only checks that you don't use invalid digits for given base. It can't detect what base the string is, except for the 3 predefined prefixes, but that only works if you pass 0 as base. Otherwise 011 will still be treated as decimal if you pass 10 as base, though it was probably intended as octal.

aha_1980

Hi @Infinity,

as the docu states, the is no binary prefix evaluation, probably because C never had it.

But if you state base 2 explicitly, it should work if the string only contains 0 and 1.

Regards

Chris Kawa

Those ifs in ::setIntString() are wrong. You can't detect the base like that. For example 0 could be binary, octal, decimal, anything from base 1 up really and all those ifs will return true. It just so happens that you treat it as a base 10 first.

QString::toUint only checks that you don't use invalid digits for given base. It can't detect what base the string is, except for the 3 predefined prefixes, but that only works if you pass 0 as base. Otherwise 011 will still be treated as decimal if you pass 10 as base, though it was probably intended as octal.

Kent-Dorfman

yeah, detecting the base of a number from its string representation is somewhat haphazard unless you are prepared to adopt certain rules and create a parser specifically for that function, such as rules that mimmick the C/C++ numeric literal rules.
0x for hex
0nnn for octal
[1-9][0-9]* for decimal
and i dunno for binary because I always use hex instead