How to remove whitespace in a sentence using remove command in C++?

Question

I get a file as input and I read the first line like this (quotes mark the begin and end, but are not in the file):

"      1,     2.0,     3.0,     4.0                         "

When I use the remove command like this:

    astring = line;
    cout << endl << "Before trim: " << line << endl;
    remove(astring.begin(), astring.end(), ' ');
    cout << endl << "After trim: " << astring << endl;

I got the output as:

1,2.0,3.0,4.02.0,    3.0,     4.0

I need the output as 1,2.0,3.0,4.0 only. What is the problem here?

Looks like the tab character.

Loki Astari
– Loki Astari

2011-07-11 07:01:50 +00:00
Commented Jul 11, 2011 at 7:01 — Loki Astari
– Loki Astari, Commented Jul 11, 2011 at 7:01

James McNellis · Accepted Answer · 2011-07-11 04:32:46Z

7

std::remove just moves all of the non-removed elements forward in the sequence; you then need to truncate the underlying container, using erase:

s.erase(std::remove(s.begin(), s.end(), ' '), s.end());

This is called the erase-remove idiom. remove cannot truncate the underlying container itself because it doesn't have a reference to the container; it only has iterators to elements in the container.

answered Jul 11, 2011 at 4:32

James McNellis

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2 Comments

Greg Hewgill Over a year ago

I have to say, this is one of the weirdest things about the C++ standard library containers.

James McNellis Over a year ago

@Greg: Yeah, the name remove is not really intuitive. One way to look at it though is that operations on the elements in a container are generally non-member algorithms, but operations on containers themselves are generally member functions on the container classes.

shelby wallace · Accepted Answer · 2012-12-25 07:29:14Z

0

James was correct in his answer and it saved me a lot of work. td::remove just moves all of the non-removed elements forward in the sequence; you then need to truncate the underlying container, using erase:

std.erase(std::remove(s.begin(), s.end(), ' '), s.end()); This is called the erase-remove idiom. remove cannot truncate the underlying container itself because it doesn't have a reference to the container; it only has iterators to elements in the container.

answered Dec 25, 2012 at 7:29

shelby wallace

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