CODEWITHSUNDEEP
regexqstringqregexp
bandito40
bandito40

Reputation: 637

QRegExp remove line with text from QString

I would like to remove all lines from a QString that have text and keep the ones that are numbers.

Prior to running a regexp my QString output be as so:

hello

1

world

2

if I ran something like

QString.remove(QRegExp("(^[a-z]*\\n$)"))

my QString output would be:

1

2

Upvotes: 1

Views: 679

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627327

Since QRegExp does not have a Perl-like /m modifier, you need to use groups like (^|\n) and ($|\n) instead. Also, bearing in mind linebreaks may include carriage returns, I'd use something like

(^|\r?\n)[a-z]*\r?\n(\r?\n|$)

See the regex demo

Qt:

QString t = "hello\n\n1\n\nworld\n\n2";
t.replace(QRegExp("(^|\r?\n)[a-z]*\r?\n(\r?\n|$)"), "\\1");

NOTE that this code will only remove lines that only consist of lowercase ASCII letters and a linebreak after them. If you need to just remove all lines that are not numeric, use QRegExp("(^|\r?\n)[^\\d\n]+\r?\n(\r?\n|$)") where [^\d\n] matches any non-digit character and not a newline.

Upvotes: 1

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