prevent from printing extra whitespace at the end of my line C++

Question

so I'm taking in input by

string input,word;
while(getline(cin, input)) {
 stringstream ss; 
 ss<<input
 while(ss >> word)
 ...

and printing the stuff I want by cout <<word<<" ";

However, when I do this it creates an extra whitespace at the end of each line and I don't want that. If I don't put that whitespace there there will be no spaces between words when I print them out. Is there an easier way to cout the words I want so that they are automatically spaced? What are some of the things I could do to prevent the extra whitespace at the end of each line.

Similar to this: https://stackoverflow.com/questions/35858896/c-compare-and-replace-last-character-of-stringstream/35859132#35859132 and this: https://stackoverflow.com/questions/36137997/convert-vectorunsigned-char-1-2-3-into-string-1-2-3-as-digits/36138229#36138229 — Galik, Jun 02 '16 at 20:40
Right now you're putting the white-space after the word. You could fix this by printing the first word outside of the while loop, and then printing the whitespace *before* the each word. Handling the first word separately will avoid a leading whitespace. — aquirdturtle, Jun 02 '16 at 20:41

score 5 · Answer 1 · answered Jun 02 '16 at 20:51

5

Test the first word extraction outside the loop, then continue the loop with leading spaces:

std::string input;
while(getline(std::cin, input))
{
    std::istringstream ss(input);
    std::string word;
    if (ss >> word)
    {
        std::cout << word;
        while (ss >> word)
            std::cout << ' ' << word;
        std::cout << '\n';
    }
}

Note: newline added for line completion. Use or delete at your discretion.

answered Jun 02 '16 at 20:51

WhozCraig

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This method only works for some cases due to the nature of what I want to do. Let's say I need to create a new line only if the input I read in is ";" if I'm given input that consists of multiple lines with only 1 word that are not ";" I need to print them in one line with a space between each word. If I do this, all those words will have no spaces in between. – Gui Montag Jun 03 '16 at 01:40
@GuiMontag This method works for *exactly* the problem your question described. If you need something else, the question should reflect that. In your comment "Let's say I need.... only if...", the very presence of "only if" constitute additional boolean checks and actions therein. Those checks simply need to be translated into code. – WhozCraig Jun 03 '16 at 09:58

score 2 · Answer 2 · answered Jun 02 '16 at 21:01

2

Flip the problem around. Instead of appending a space, figure out when you should prepend a space.

The way I do this is to initialize a prefix delimiter to an empty value, then set it to something valid after the first element. In your case, it would be like this:

const char *delimiter= "";
while(ss >> word)
{
    ss >> delimiter >> word;
    delimiter= " ";
}

answered Jun 02 '16 at 21:01

MSN

53,214
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Thanks dude, I think your solution passed most of my testing – Gui Montag Jun 03 '16 at 02:28

coyotte508 · Answer 3 · 2016-06-02T23:32:52.173

0

A trick - which still feels a bit frustrating - is adding a boolean variable in the mix:

bool space = false;
while (ss >> word) {
    if (space) {
         cout << " ";
    } else {
         space = true;
    }

    cout << word;
}

edited Jun 02 '16 at 23:32

answered Jun 02 '16 at 20:38

coyotte508

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Sadly the second example doesn't work. It exhibits the same problem. – Galik Jun 02 '16 at 20:46
I tried the first method and I got the same problem. I'm not sure why though. Shouldn't the loop stop once input stops? – Gui Montag Jun 02 '16 at 21:06
@Galik, thanks removed. @Gui Montag you should put this code as replacement of your `while(ss >> word)` and there should be no difference in reading the input... – coyotte508 Jun 02 '16 at 23:34

prevent from printing extra whitespace at the end of my line C++

3 Answers3