Complete demo for QString
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#include <QtGui>
#include <QApplication>
#include <stdio.h>
class Widget : public QWidget
{
public:
Widget(QWidget *parent = 0);
void constCharPointer();
void constCharArray();
void characterReference();
void atFunction();
void stringLiteral();
void modify();
void index();
QString boolToString(bool b);
void nullVsEmpty();
void appendFunction();
void argFunction();
void chopFunction();
void compareFunction();
void compareSensitiveFunction();
void containsFunction();
void countFunction();
void dataFunction();
void endsWithFunction();
void fillFunction();
void fromRawDataFunction();
void indexOfFunction();
void firstIndexOfFunction();
void insertFunction();
void isNullFunction();
void isEmptyFunction();
void lastIndexOfFunction();
void leftFunction();
void leftJustifiedFunction();
void leftRefFunction();
void midFunction();
void midRefFunction();
void numberFunction();
void prependFunction();
void removeFunction();
void replaceFunction();
void reserveFunction();
void resizeFunction();
void rightFunction();
void rightJustifiedFunction();
void rightRefFunction();
void sectionFunction();
void setNumFunction();
void simplifiedFunction();
void sizeFunction();
void splitFunction();
void splitCaseSensitiveFunction();
void sprintfFunction();
void startsWithFunction();
void toDoubleFunction();
void toFloatFunction();
void toIntFunction();
void toLongFunction();
void toLongLongFunction();
void toLowerFunction();
void toShortFunction();
void toUIntFunction();
void toULongFunction();
void toULongLongFunction();
void toUShortFunction();
void toUpperFunction();
void trimmedFunction();
void truncateFunction();
void plusEqualOperator();
void arrayOperator();
};
Widget::Widget(QWidget *parent)
: QWidget(parent)
{
}
void Widget::constCharPointer()
{
QString str = "Hello";
}
void Widget::constCharArray()
{
static const QChar data[4] = { 0x0055, 0x006e, 0x10e3, 0x03a3 };
QString str(data, 4);
}
void Widget::characterReference()
{
QString str;
str.resize(4);
str[0] = QChar('U');
str[1] = QChar('n');
str[2] = QChar(0x10e3);
str[3] = QChar(0x03a3);
}
void Widget::atFunction()
{
QString str;
for (int i = 0; i < str.size(); ++i) {
if (str.at(i) >= QChar('a') && str.at(i) <= QChar('f'))
qDebug() << "Found character in range [a-f]";
}
}
void Widget::stringLiteral()
{
QString str;
if (str == "auto" || str == "extern"
|| str == "static" || str == "register") {
// ...
}
}
void Widget::modify()
{
QString str = "and";
str.prepend("rock "); // str == "rock and"
str.append(" roll"); // str == "rock and roll"
str.replace(5, 3, "&"); // str == "rock & roll"
}
void Widget::index()
{
QString str = "We must be <b>bold</b>, very <b>bold</b>";
int j = 0;
while ((j = str.indexOf("<b>", j)) != -1) {
qDebug() << "Found <b> tag at index position" << j;
++j;
}
}
QString Widget::boolToString(bool b)
{
QString result;
if (b)
result = "True";
else
result = "False";
return result;
}
void Widget::nullVsEmpty()
{
QString().isNull(); // returns true
QString().isEmpty(); // returns true
QString("").isNull(); // returns false
QString("").isEmpty(); // returns true
QString("abc").isNull(); // returns false
QString("abc").isEmpty(); // returns false
}
void Widget::appendFunction()
{
QString x = "free";
QString y = "dom";
x.append(y);
// x == "freedom"
x.insert(x.size(), y);
}
void Widget::argFunction()
{
QString i; // current file's number
QString total; // number of files to process
QString fileName; // current file's name
QString status = QString("Processing file %1 of %2: %3")
.arg(i).arg(total).arg(fileName);
QString str;
str = "%1 %2";
str.arg("%1f", "Hello"); // returns "%1f Hello"
str.arg("%1f").arg("Hello"); // returns "Hellof %2"
str = QString("Decimal 63 is %1 in hexadecimal")
.arg(63, 0, 16);
// str == "Decimal 63 is 3f in hexadecimal"
QLocale::setDefault(QLocale(QLocale::English, QLocale::UnitedStates));
str = QString("%1 %L2 %L3")
.arg(12345)
.arg(12345)
.arg(12345, 0, 16);
// str == "12345 12,345 3039"
}
void Widget::chopFunction()
{
QString str("LOGOUT\r\n");
str.chop(2);
// str == "LOGOUT"
}
void Widget::compareFunction()
{
int x = QString::compare("auto", "auto"); // x == 0
int y = QString::compare("auto", "car"); // y < 0
int z = QString::compare("car", "auto"); // z > 0
}
void Widget::compareSensitiveFunction()
{
int x = QString::compare("aUtO", "AuTo", Qt::CaseInsensitive); // x == 0
int y = QString::compare("auto", "Car", Qt::CaseSensitive); // y > 0
int z = QString::compare("auto", "Car", Qt::CaseInsensitive); // z < 0
}
void Widget::containsFunction()
{
QString str = "Peter Pan";
str.contains("peter", Qt::CaseInsensitive); // returns true
}
void Widget::countFunction()
{
QString str = "banana and panama";
str.count(QRegExp("a[nm]a")); // returns 4
}
void Widget::dataFunction()
{
QString str = "Hello world";
QChar *data = str.data();
while (!data->isNull()) {
qDebug() << data->unicode();
++data;
}
}
void Widget::endsWithFunction()
{
QString str = "Bananas";
str.endsWith("anas"); // returns true
str.endsWith("pple"); // returns false
}
void Widget::fillFunction()
{
QString str = "Berlin";
str.fill('z');
// str == "zzzzzz"
str.fill('A', 2);
// str == "AA"
}
void Widget::fromRawDataFunction()
{
QRegExp pattern;
static const QChar unicode[] = {
0x005A, 0x007F, 0x00A4, 0x0060,
0x1009, 0x0020, 0x0020};
int size = sizeof(unicode) / sizeof(QChar);
QString str = QString::fromRawData(unicode, size);
if (str.contains(QRegExp(pattern))) {
// ...
}
}
void Widget::indexOfFunction()
{
QString x = "sticky question";
QString y = "sti";
x.indexOf(y); // returns 0
x.indexOf(y, 1); // returns 10
x.indexOf(y, 10); // returns 10
x.indexOf(y, 11); // returns -1
}
void Widget::firstIndexOfFunction()
{
QString str = "the minimum";
str.indexOf(QRegExp("m[aeiou]"), 0); // returns 4
}
void Widget::insertFunction()
{
QString str = "Meal";
str.insert(1, QString("ontr"));
// str == "Montreal"
}
void Widget::isEmptyFunction()
{
QString().isEmpty(); // returns true
QString("").isEmpty(); // returns true
QString("x").isEmpty(); // returns false
QString("abc").isEmpty(); // returns false
}
void Widget::isNullFunction()
{
QString().isNull(); // returns true
QString("").isNull(); // returns false
QString("abc").isNull(); // returns false
}
void Widget::lastIndexOfFunction()
{
QString x = "crazy azimuths";
QString y = "az";
x.lastIndexOf(y); // returns 6
x.lastIndexOf(y, 6); // returns 6
x.lastIndexOf(y, 5); // returns 2
x.lastIndexOf(y, 1); // returns -1
QString str = "the minimum";
str.lastIndexOf(QRegExp("m[aeiou]")); // returns 8
}
void Widget::leftFunction()
{
QString x = "Pineapple";
QString y = x.left(4); // y == "Pine"
}
void Widget::leftJustifiedFunction()
{
QString s = "apple";
QString t = s.leftJustified(8, '.'); // t == "apple..."
QString str = "Pineapple";
str = str.leftJustified(5, '.', true); // str == "Pinea"
}
void Widget::midFunction()
{
QString x = "Nine pineapples";
QString y = x.mid(5, 4); // y == "pine"
QString z = x.mid(5); // z == "pineapples"
}
void Widget::numberFunction()
{
long a = 63;
QString s = QString::number(a, 16); // s == "3f"
QString t = QString::number(a, 16).toUpper(); // t == "3F"
}
void Widget::prependFunction()
{
QString x = "ship";
QString y = "air";
x.prepend(y);
// x == "airship"
}
void Widget::removeFunction()
{
QString s = "Montreal";
s.remove(1, 4);
// s == "Meal"
QString t = "Ali Baba";
t.remove(QChar('a'), Qt::CaseInsensitive);
// t == "li Bb"
QString r = "Telephone";
r.remove(QRegExp("[aeiou]."));
// r == "The"
}
void Widget::replaceFunction()
{
QString x = "Say yes!";
QString y = "no";
x.replace(4, 3, y);
// x == "Say no!"
QString str = "colour behaviour flavour neighbour";
str.replace(QString("ou"), QString("o"));
// str == "color behavior flavor neighbor"
QString s = "Banana";
s.replace(QRegExp("a[mn]"), "ox");
// s == "Boxoxa"
QString t = "A <i>bon mot</i>.";
t.replace(QRegExp("<i>([^<]*)</i>"), "\\emph{\\1}");
// t == "A \\emph{bon mot}."
QString equis = "xxxxxx";
equis.replace("xx", "x");
// equis == "xxx"
}
void Widget::reserveFunction()
{
QString result;
int maxSize;
bool condition;
QChar nextChar;
result.reserve(maxSize);
while (condition)
result.append(nextChar);
result.squeeze();
}
void Widget::resizeFunction()
{
QString s = "Hello world";
s.resize(5);
// s == "Hello"
s.resize(8);
// s == "Hello???" (where ? stands for any character)
QString t = "Hello";
t += QString(10, 'X');
// t == "HelloXXXXXXXXXX"
QString r = "Hello";
r = r.leftJustified(10, ' ');
// r == "Hello "
}
void Widget::rightFunction()
{
QString x = "Pineapple";
QString y = x.right(5); // y == "apple"
}
void Widget::rightJustifiedFunction()
{
QString s = "apple";
QString t = s.rightJustified(8, '.'); // t == "...apple"
QString str = "Pineapple";
str = str.rightJustified(5, '.', true); // str == "Pinea"
}
void Widget::sectionFunction()
{
QString str;
QString csv = "forename,middlename,surname,phone";
QString path = "/usr/local/bin/myapp"; // First field is empty
QString::SectionFlag flag = QString::SectionSkipEmpty;
str = csv.section(',', 2, 2); // str == "surname"
str = path.section('/', 3, 4); // str == "bin/myapp"
str = path.section('/', 3, 3, flag); // str == "myapp"
str = csv.section(',', -3, -2); // str == "middlename,surname"
str = path.section('/', -1); // str == "myapp"
QString data = "forename**middlename**surname**phone";
str = data.section("**", 2, 2); // str == "surname"
str = data.section("**", -3, -2); // str == "middlename**surname"
QString line = "forename\tmiddlename surname \t \t phone";
QRegExp sep("\\s+");
str = line.section(sep, 2, 2); // s == "surname"
str = line.section(sep, -3, -2); // s == "middlename surname"
}
void Widget::setNumFunction()
{
QString str;
str.setNum(1234); // str == "1234"
}
void Widget::simplifiedFunction()
{
QString str = " lots\t of\nwhitespace\r\n ";
str = str.simplified();
// str == "lots of whitespace";
}
void Widget::sizeFunction()
{
QString str = "World";
int n = str.size(); // n == 5
str.data()[0]; // returns 'W'
str.data()[4]; // returns 'd'
str.data()[5]; // returns '\0'
}
void Widget::splitFunction()
{
QString str;
QStringList list;
str = "Some text\n\twith strange whitespace.";
list = str.split(QRegExp("\\s+"));
// list: [ "Some", "text", "with", "strange", "whitespace." ]
str = "This time, a normal English sentence.";
list = str.split(QRegExp("\\W+"), QString::SkipEmptyParts);
// list: [ "This", "time", "a", "normal", "English", "sentence" ]
str = "Now: this sentence fragment.";
list = str.split(QRegExp("\\b"));
// list: [ "", "Now", ": ", "this", " ", "sentence", " ", "fragment", "." ]
}
void Widget::splitCaseSensitiveFunction()
{
QString str = "a,,b,c";
QStringList list1 = str.split(",");
// list1: [ "a", "", "b", "c" ]
QStringList list2 = str.split(",", QString::SkipEmptyParts);
// list2: [ "a", "b", "c" ]
}
void Widget::sprintfFunction()
{
size_t BufSize;
char buf[BufSize];
::snprintf(buf, BufSize, "%lld", 123456789LL);
QString str = QString::fromAscii(buf);
QString result;
QTextStream(&result) << "pi = " << 3.14;
// result == "pi = 3.14"
}
void Widget::startsWithFunction()
{
QString str = "Bananas";
str.startsWith("Ban"); // returns true
str.startsWith("Car"); // returns false
}
void Widget::toDoubleFunction()
{
QString str = "1234.56";
double val = str.toDouble(); // val == 1234.56
bool ok;
double d;
d = QString( "1234.56e-02" ).toDouble(&ok); // ok == true, d == 12.3456
QLocale::setDefault(QLocale::C);
d = QString( "1234,56" ).toDouble(&ok); // ok == false
d = QString( "1234.56" ).toDouble(&ok); // ok == true, d == 1234.56
QLocale::setDefault(QLocale::German);
d = QString( "1234,56" ).toDouble(&ok); // ok == true, d == 1234.56
d = QString( "1234.56" ).toDouble(&ok); // ok == true, d == 1234.56
QLocale::setDefault(QLocale::C);
d = QString( "1,234,567.89" ).toDouble(&ok); // ok == false
}
void Widget::toFloatFunction()
{
QString str1 = "1234.56";
str1.toFloat(); // returns 1234.56
bool ok;
QString str2 = "R2D2";
str2.toFloat(&ok); // returns 0.0, sets ok to false
}
void Widget::toIntFunction()
{
QString str = "FF";
bool ok;
int hex = str.toInt(&ok, 16); // hex == 255, ok == true
int dec = str.toInt(&ok, 10); // dec == 0, ok == false
}
void Widget::toLongFunction()
{
QString str = "FF";
bool ok;
long hex = str.toLong(&ok, 16); // hex == 255, ok == true
long dec = str.toLong(&ok, 10); // dec == 0, ok == false
}
void Widget::toLongLongFunction()
{
QString str = "FF";
bool ok;
qint64 hex = str.toLongLong(&ok, 16); // hex == 255, ok == true
qint64 dec = str.toLongLong(&ok, 10); // dec == 0, ok == false
}
void Widget::toLowerFunction()
{
QString str = "Qt by NOKIA";
str = str.toLower(); // str == "qt by nokia"
}
void Widget::toShortFunction()
{
QString str = "FF";
bool ok;
short hex = str.toShort(&ok, 16); // hex == 255, ok == true
short dec = str.toShort(&ok, 10); // dec == 0, ok == false
}
void Widget::toUIntFunction()
{
QString str = "FF";
bool ok;
uint hex = str.toUInt(&ok, 16); // hex == 255, ok == true
uint dec = str.toUInt(&ok, 10); // dec == 0, ok == false
}
void Widget::toULongFunction()
{
QString str = "FF";
bool ok;
ulong hex = str.toULong(&ok, 16); // hex == 255, ok == true
ulong dec = str.toULong(&ok, 10); // dec == 0, ok == false
}
void Widget::toULongLongFunction()
{
QString str = "FF";
bool ok;
quint64 hex = str.toULongLong(&ok, 16); // hex == 255, ok == true
quint64 dec = str.toULongLong(&ok, 10); // dec == 0, ok == false
}
void Widget::toUShortFunction()
{
QString str = "FF";
bool ok;
ushort hex = str.toUShort(&ok, 16); // hex == 255, ok == true
ushort dec = str.toUShort(&ok, 10); // dec == 0, ok == false
}
void Widget::toUpperFunction()
{
QString str = "TeXt";
str = str.toUpper(); // str == "TEXT"
}
void Widget::trimmedFunction()
{
QString str = " lots\t of\nwhitespace\r\n ";
str = str.trimmed();
// str == "lots\t of\nwhitespace"
}
void Widget::truncateFunction()
{
QString str = "Vladivostok";
str.truncate(4);
// str == "Vlad"
}
void Widget::plusEqualOperator()
{
QString x = "free";
QString y = "dom";
x += y;
// x == "freedom"
}
void Widget::arrayOperator()
{
QString str;
if (str[0] == QChar('?'))
str[0] = QChar('_');
}
void Widget::midRefFunction()
{
//! [midRef]
QString x = "Nine pineapples";
QStringRef y = x.midRef(5, 4); // y == "pine"
QStringRef z = x.midRef(5); // z == "pineapples"
//! [midRef]
}
void Widget::leftRefFunction()
{
//! [leftRef]
QString x = "Pineapple";
QStringRef y = x.leftRef(4); // y == "Pine"
//! [leftRef]
}
void Widget::rightRefFunction()
{
//! [rightRef]
QString x = "Pineapple";
QStringRef y = x.rightRef(5); // y == "apple"
//! [rightRef]
}
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Widget widget;
widget.show();
return app.exec();
}
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