I'm trying to do a simple task of reading space separated numbers from console into a vector<int>
, but I'm not getting how to do this properly.
This is what I have done till now:
int n = 0;
vector<int> steps;
while(cin>>n)
{
steps.push_back(n);
}
However, this requires the user to press an invalid character (such as a
) to break the while
loop. I don't want it.
As soon as user enters numbers like 0 2 3 4 5
and presses Enter
I want the loop to be broken. I tried using i开发者_如何学Pythonstream_iterator
and cin.getline
also, but I couldn't get it working.
I don't know how many elements user will enter, hence I'm using vector
.
Please suggest the correct way to do this.
Use a getline
combined with an istringstream
to extract the numbers.
std::string input;
getline(cin, input);
std::istringstream iss(input);
int temp;
while(iss >> temp)
{
yourvector.push_back(temp);
}
To elaborate on jonsca's answer, here is one possibility, assuming that the user faithfully enters valid integers:
string input;
getline(cin, input);
istringstream parser(input);
vector<int> numbers;
numbers.insert(numbers.begin(),
istream_iterator<int>(parser), istream_iterator<int>());
This will correctly read and parse a valid line of integers from cin
. Note that this is using the free function getline
, which works with std::string
s, and not istream::getline
, which works with C-style strings.
This code should help you out, it reads a line to a string and then iterates over it getting out all numbers.
#include <iostream>
#include <sstream>
#include <string>
int main() {
std::string line;
std::getline(std::cin, line);
std::istringstream in(line, std::istringstream::in);
int n;
vector<int> v;
while (in >> n) {
v.push_back(n);
}
return 0;
}
Also, might be helpful to know that you can stimulate an EOF - Press 'ctrl-z' (windows only, unix-like systems use ctrl-d) in the command line, after you have finished with your inputs. Should help you when you're testing little programs like this - without having to type in an invalid character.
Prompt user after each number or take number count in advance and loop accordingly. Not a great idea but i saw this in many applications.
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