QT Common class--qstring

Qstring has some aspects with the use of string in C + +, such as appending a string to another string, and also using "+". There are also append functions and so on.

Here is an example of some of the qstring specific functions that are commonly used:

The Qstring class of QT provides a convenient interface for string manipulation.

Causes a character to fill a string, meaning that all characters in the string are replaced by the equal-length ch.

Qstring::fill (Qchar ch, int size =-1)

Cases:

QString str = "Berlin"; Str.fill (' z '); str = = "Zzzzzz"  str.fill (' A ', 2);//str = = "AA"

2, find the same string str from the string.

int Qstring::indexof (const QString & str, int from = 0, qt::casesensitivity cs = qt::casesensitive) const

For example:

QString x = "Sticky question"; QString y = "sti"; X.indexof (y); Returns 0 X.indexof (y, 1); Returns X.indexof (Y, 10); Returns X.indexof (Y, 11); Returns-1

3 Inserting a string at the specified location

QString & Qstring::insert (int position, const QString & str)

For example:

QString str = "Meal"; Str.insert (1, QString ("Ontr")); str = = "Montreal"

3 to determine if the string is empty.

BOOL Qstring::isempty () const

4. Determine if the string exists.

BOOL Qstring::isnull () const

5, the string is truncated from left to right

QString qstring::left (int n) const

For example:

QString x = "Pineapple"; QString y = x.left (4); y = = "Pine"

6. Intercept the string from the middle.

QString qstring::mid (int position, int n =-1) const

For example:

QString x = "Nine pineapples"; QString y = X.mid (5, 4); y = = "Pine" QString z = x.mid (5); z = = "Pineapples"

7. Remove a character from the middle of the string.

QString & Qstring::remove (int position, int n)

For example:

QString s = "Montreal"; S.remove (1, 4); s = = "Meal"

8, replace some characters in the string.

QString & Qstring::replace (int position, int n, const QString & After)

For example:

QString x = "Say yes!"; QString y = "no"; X.replace (4, 3, y); x = = "Say no!"

9, cutting a string with a character. (frequently used recently)

QString qstring::section (qchar Sep, int start, int end =-1, sectionflags flags = sectiondefault) const

10, convert integer, float, or other type to qstring

QString & Qstring::setnum (uint n, int base = 10)

If we want to check whether a string starts or ends with something, we can use the StartsWith () and EndsWith () functions: if (Url.startswith ("http:") && Url.endswith (". PNG "))    

　　

QT Common class--qstring