How to get a first word of from a Qstring

Question

I want to get first word of a Qstring.

For example String1 = "Read from file1". I want to extract string2 = "Read". I want to extract substring based on whitespace.

If I encounter a first whitespace in my string1, I need that part of string1 to string2.

You should provide some code, how you try to solve your problem. — Dmitry Sazonov, Feb 06 '14 at 14:49

score 6 · Answer 1 · edited Apr 11 '16 at 20:07

6

Use the split function of QString in this way:

QString firstWord = string1.split(" ").at(0);

If there is no whitespace in the string, the whole string will be returned.

edited Apr 11 '16 at 20:07

Angie Quijano

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answered Feb 06 '14 at 13:52

Rud Limaverde

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You’d better check if it’s not empty before calling at(0) – Frank Osterfeld Feb 06 '14 at 16:58
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In the docs it says that if there is no occurrence, the split() returns a single-element list containing the string itself. So it will always return at least a one element list. – Rud Limaverde Feb 06 '14 at 19:44
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Indeed, it even does that when splitting a null string. – Frank Osterfeld Feb 06 '14 at 20:09

Alex P · Answer 2 · 2019-05-08T11:45:59.957

5

Use QString::split if you want to use all the parts, or QString::section if you just want to grab the first word.

For example, the most basic syntax is:

QString str = "Do re mi";
QString firstWord = str.section(" ", 0, 0);
// firstWord = "Do"

If you need to handle all kinds of weird whitespace, you can use the regex version of the functions:

QString str = "\tDo    re\nmi"; // tabs and newlines and spaces, oh my!
QString firstWord = str.section(QRegExp("\\s+"), 0, 0, 
    QString::SectionSkipEmpty);
// firstWord = "Do"

edited May 08 '19 at 11:45

answered Feb 06 '14 at 14:04

Alex P

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"If end is not specified, all fields from position start to the end of the string are included", so it has to be `firstWord = str.section(" ", 0, 0);`, right? – user1712200 May 08 '19 at 11:40
@user1712200 Seems so. Good catch. – Alex P May 08 '19 at 11:46

score 1 · Answer 3 · answered Feb 06 '14 at 13:55

1

I would do:

QString s("Read from file1");
QString subStr = s.section(" ", 0, 0, QString::SectionSkipEmpty);

This will work correctly in case of such strings too:

" Read from file1 "

answered Feb 06 '14 at 13:55

vahancho

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How to get a first word of from a Qstring

3 Answers3