Removing whitespaces inside a string

Question

I have a string lots\t of\nwhitespace\r\n which I have simplified but I still need to get rid of the other spaces in the string.

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

I can do this erase_all(str, " "); in boost but I want to remain in qt.

arnt · Accepted Answer · 2013-12-25T19:12:06.477

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str = str.simplified();
str.replace( " ", "" );

The first changes all of your whitespace characters to a single instance of ASCII 32, the second removes that.

edited Dec 25 '13 at 19:12

answered Nov 24 '11 at 11:24

arnt

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@noone in that case you should probably make a simple test case and report a bug, because according to the documentation it still ought to. – arnt Aug 29 '18 at 11:16
sorry. My bad . I had not included QString – Aug 29 '18 at 12:26

Terrabits · Answer 2 · 2018-07-12T21:31:03.517

13

Option 1:

Simplify the white space, then remove it

Per the docs

[QString::simplified] Returns a string that has whitespace removed from the start and the end, and that has each sequence of internal whitespace replaced with a single space.

Once the string is simplified, the white spaces can easily be removed.

str.simplified().remove(' ')

Option 2:

Use a QRegExp to capture all types of white space in remove.

QRegExp space("\\s");
str.remove(space);

Notes

The OPs string has white space of different types (tab, carriage return, new line), all of which need to be removed. This is the tricky part.
QString::remove was introduced in Qt 5.6; prior to 5.6 removal can be achieved using QString::replace and replacing the white space with an empty string "".

edited Jul 12 '18 at 21:31

answered Mar 06 '14 at 00:42

Terrabits

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Is simplified() necessary here? Surely remove(" ") will do the job? – Iron Attorney Jul 12 '18 at 14:57
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@IronAttorney Depending on the approach, yes. I've added clarification to my answer and an alternative solution that does not require `simplified`. – Terrabits Jul 12 '18 at 21:31

score 13 · Answer 3 · answered Nov 24 '11 at 11:22

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Try this:

str.replace(" ","");

answered Nov 24 '11 at 11:22

tonekk

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score 0 · Answer 4 · answered Jun 07 '18 at 09:17

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You can omit the call to simplified() with a regex:

str.replace(QRegularExpression("\\s+"), QString());

I don't have measured which method is faster. I guess this regex would perform worse.

answered Jun 07 '18 at 09:17

Martin Hennings

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Removing whitespaces inside a string

4 Answers4