Learning notes for qstringlist

Hello everyone , I meet you again , I'm your friend, Quan Jun .

Due to company projects , Start Study QT, Here are some study notes , After that, I forgot to read it . Simple notes , Do not blame it. . Reference blog ：https://blog.csdn.net/u013360881/article/details/52170487

QStringList initialization

  QStringList qstrList;
  qstrList<<"Android" << "Qt Creator" << "Java" << "C++";
  QStringListIterator strIterator(qstrList);
  while (strIterator.hasNext())
        qDebug() << strIterator.next() << endl;

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Here we use QStringList add to QString character string , use << To add a string , amount to Java in List Of add() Method .

Let's learn about QList Methods

1. Add string append() QStringList Can pass append(), Or use << To add List Elements , Such as

qstrList.append("python");
qstrList << "PHP" ;

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2. Insert string insert() Insert string insert Method can insert a string into the... We specify list The location of ：

qstrList.insert(0,"C#");

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The first parameter is where we want to insert , The following parameters represent the values we want to insert . 3. Replace string replace() adopt replace() Method we can replace list The value of a position in the

qstrList.replace(0,"Web");

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The first parameter is the position we want to replace , The following parameters represent the values we want to replace . 4. Delete string removeAt(), removeFirst(), removeLast(), and removeOne() We can use the method name , Infer the specific function of the method , Select the corresponding method according to the actual needs ： Here's to say removeOne() Method , He means to delete a specific value , The parameter is us list Contents of Li , Its definition is ： bool removeOne(const T &value) , The return value is bool type , Let's write an example of usage

bool isflag = qstrList.removeOne("C#");// Delete a specified element , Delete successful return true, Delete failed return fasle
qDebug() << isflag << endl;
int n = qstrList.removeAll("Java");// Delete all specified elements , Returns the number of deleted elements 
qDebug() << n << endl;
qstrList.removeAt(2);// Delete the third element 
qstrList.removeFirst();// Delete first element 
qstrList.removeLast();// Delete the last element 

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Next let's learn QStringList Methods

1. Merge strings using join( )

QString str = fonts.join(",");
// str == "Android,Qt Creator,Java,C++"

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2. Split string

QString str = "Android,Qt Creator, ,Java,C++";
QStringList list1 = str.split(",");
// list1: [ "Android", "Qt Creator"," ", "Java", "C++" ]
QStringList list2 = str.split(",", QString::SkipEmptyParts);
// list2:[ "Android", "Qt Creator", "Java", "C++" ]

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That is to say, if there is QString：：SkipEmptyParts, Empty items will not appear in the result . By default , Blank items are reserved 3. Indexes IndexOf（） The index() function returns the index of the first occurrence of a given string . and lastIndexOf（） function , Returns the index of the last occurrence of a string .

QStringList qstrList;
 qstrList<<"Java" << "Android" << "Qt Creator" << "Java" << "C++";
int index = qstrList.indexOf("Java");// return  0
int index = qstrList.indexOf("Java");// return  3

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4. Replace replaceInStrings（）

QStringList files;
files << "$file/src/moc/moc.y" <<  "$file/src/moc/moc.l" <<  "$file/include/qconfig.h";
files.replaceInStrings("$file", "/usr/file");
// files: [ "/usr/file/src/moc/moc.y", ...]

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5. Filter filter（） Allows you to extract a new list containing only those strings containing a specific string （ Or match a specific regular expression ）：

QStringList list;
list << "Bill Murray" << "John Doe" << "Bill Clinton";
QStringList result;
result = list.filter("Bill");
// result: ["Bill Murray", "Bill Clinton"]

// When comparing strings  
//Qt::CaseSensitive   Search is case sensitive 
//Qt::CaseInSensitive    Case insensitive 
result = list.filter("bill",Qt::CaseInSensitive);
// result: ["Bill Murray", "Bill Clinton"]

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summary ：

QStringList Class provides a list of strings .QStringList Inherited from QList < QString >. And QList equally ,QStringList Is implicitly shared . It provides fast index based access , And quick insert and delete . Passing a list of strings as a value parameter is fast and safe .QList All functions of the also apply to QStringList. for example , You can use isEmpty（） To test whether the list is empty , You can call things like append（）、prepend（）、insert（）、replace（）、removeAll（）、removeAt（）、removeFirst（） and removeOne（） To modify the QStringList Function of . Besides ,QStringList Provides some convenient functions , Make it easier to handle lists of strings

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