Using cin.get() in a loop to input a string

Question

I was wondering if there is a way of using the cin.get() fuction in a loop to read a string that could be composed of more than one word.

For example

while (cin.get(chr)) // This gets stuck asking the user for input

while (cin.get(chr) && chr != '\n') // This code doesn't allow the '\n' to be read inside the loop

I want to be able to read a whole string and be able to use my chr variable to determine if the current character being read is a '\n' character.

I'm a little familiar with the getline function. But I don't know of a way to individually go through every character in the string while counting them when using the getline. I hope what I'm saying makes sense. I'm new to programming and c++.

I basically want to determine when these characters ( ' ' , '\n') happen in my string. I will use this to determine when a word ends and a new one begins in my string.

"I will use this to determine when a word ends and a new one begins in my string" - then why not read the input word-by-word instead? That is how operator>> reads by default, ie string word; while (cin >> word) { ... }. Or, if you want to read words in a single line: string line, word; while (getline(cin, line)) { istringstream iss(line); while (iss >> word) { ... }} — Remy Lebeau
– Remy Lebeau, Commented Oct 14, 2019 at 20:44

Lukas-T · Accepted Answer · 2019-10-14 18:44:00Z

2

If you want to read a whole line and count the spaces in it you can use getline.

std::string s;
std::getline(std::cin, s);

//count number of spaces
auto spaces = std::count_if(s.begin(), s.end(), [](char c) {return std::isspace(c);});

std::getline will always read until it encounters an \n.

answered Oct 14, 2019 at 18:44

Lukas-T

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4 Comments

Rokas Višinskas Over a year ago

why not simply auto spaces = std::count(begin(s), end(s), ' ');?

Lukas-T Over a year ago

Because there are more characters than ' ' that can be classified as a space. For example a tab. I agree that it might be more than is needed in most cases.

Rokas Višinskas Over a year ago

Thanks, I wasn't familiar with the purpose of std::isspace.

Remy Lebeau Over a year ago

"std::getline will always read until it encounters an \n" - or a user-defined delimiter. \n is just the default delimiter

Josh W. · Accepted Answer · 2019-10-14 18:39:18Z

1

You could try the following:

using namespace std;

int main() {
    char ch;
    string str = "";
    while (cin.get(ch) && ch != '\n')
        str += ch;
    cout << str;
}

and the string str would have all characters till end line.

answered Oct 14, 2019 at 18:39

Josh W.

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