Random Integer List
开发者_如何转开发If I had a list of integers separated by a space on one line (eg: 50 34 1 3423 5 345) then what would be the best way of making each of them a separate integer variable - collecting the list of integers with cin
?
#include <iostream>
#include <vector>
#include <iterator>
std::vector<int> ints;
std::copy(std::istream_iterator<int>(cin),
std::istream_iterator<int>(),
std::back_inserter(ints));
Done. If you really need to explicetely read line-wise:
#include <sstream>
#include <iostream>
#include <vector>
#include <iterator>
std::string singleline;
std::istringstream iss; // out of loop for performance
while (std::getline(cin, singleline))
{
iss.str(singleline);
std::copy(std::istream_iterator<int>(iss),
std::istream_iterator<int>(),
std::back_inserter(ints));
}
An istream_iterator<int>
will repeatedly apply operator>>(int&)
to the referenced stream (until the end of the stream). By default this will silently ignore whitespace, and it will throw an exception if the input operation failed (e.g. non-integer input is encountered)
The back_inserter is an output iterator that you can use with all container types (like vector
) that support the .push_back
operation. So in fact what is written there in STL algorithmese is similar to
std::vector<int> ints;
while (iss>>myint)
{
ints.push_back(myint);
}
In follow-up to sehe's answer, here's how you'd do it a little more verbosely (ahem).
The algorithms sehe used basically do this internally. This answer is included mostly for clarity.
#include <iostream>
#include <vector>
int main()
{
std::vector<int> myInts;
int tmp;
while (std::cin >> tmp) {
myInts.push_back(tmp);
}
// Now `myInts` is a vector containing all the integers
}
Live example.
Have a look at the man pages for strtok( )
and atoi( )
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