Qt string interception common function

1, bool QString :: startsWith // string begins XX, returns true, the second parameters can be set case-sensitive

QString str = "Bananas";
str.startsWith("Ban");     // returns true
str.startsWith("Car");     // returns false

 

2, bool QString :: endsWith // string ends XX, returns false, the second parameters can be set case-sensitive

QString str = "Bananas";
str.endsWith("anas");         // returns true
str.endsWith("pple");         // returns false

 

3, QString QString :: trimmed () // return with no spaces before and after the string

QString str = "  lots\t of\nwhitespace\r\n ";
str = str.trimmed();
// str == "lots\t of\nwhitespace"

 

4, QString & QString :: remove (int position, int n) // specify the location to start deleting n characters, returns that character references

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

 

5, int QString :: indexOf () // Returns the index position specified position from the beginning of the first occurrence, or -1 not found. The second parameter may be set case-sensitive

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

 

6、int QString::lastIndexOf()　

// returns the index of the last occurrence of the string str in this string, searching backward from index position. If from is -1 (the default), the search starts from the last character; if from is -2, the penultimate character, and so on. If str is not found, returns -1. The second parameter may be set case-sensitive

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

 

7, QString QString :: right (int n) const // Returns a substring of the rightmost string of n characters.

QString x = "Pineapple";
QString y = x.right(5);      // y == "apple"

 

8, QString QString :: left (int n) const // Returns a substring of the string leftmost n characters.

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

 

9, QString QString :: mid (int position, int n = -1) const // Returns a string containing n characters of the string, starting from a position specified by the index.

QString x = "Nine pineapples";
QString y = x.mid(5, 4);            // y == "pine"
QString z = x.mid(5);               // z == "pineapples"