string s1 = "bob";
string s2 = "hey";
string s3 = "joe";
string s4 = "doe";
vector<string> myVec;
myVec.push_back(s1);
myVec.push_back(s2);
myVec.push_back(s3);
myVec.push_back(s4);
How do I output "bob hey" "bob hey joe" "bob hey joe doe" using an iterator on myVec?
Any help hints or help would be appreciated
The following should work:
for (auto it = myVec.begin(), end = myVec.end(); it != end; ++it)
{
for (auto it2 = myVec.begin(); it2 != (it + 1); ++it2)
{
std::cout << *it2 << " ";
}
std::cout << "\n";
}
Example output:
bob
bob hey
bob hey joe
bob hey joe doe
using namespace std;
auto it_first = begin(myVec);
auto it_last = begin(myVec) + 2;
while (it_last != end(myVec))
for_each(it_first, it_last++, [](string const & str) { cout << str << " "; });
cout << endl;
}
This should do it. EDIT: Corrected bug :) that should give you the correct output please confirm. There was an extra next.
next? I think he wants to include the first element. Also, this might fail if the vector contains less than 2 elements.Something like this, if you can use boost:
std::vector<std::string> s { "bob", "hey", "joe", "doe" };
std::vector<std::string> d;
for (auto i = std::begin(s); i != std::end(s); ++i) {
d.push_back(boost::algorithm::join(
boost::make_iterator_range(std::begin(s), i + 1),
std::string(" ")
));
}
The output vector d will contain the following:
bob
bob hey
bob hey joe
bob hey joe doe
But more efficient solution is using temporary string:
std::vector<std::string> s { "bob", "hey", "joe", "doe" };
std::vector<std::string> d;
std::string t;
std::for_each(std::begin(s), std::end(s), [&](const std::string &i) {
d.push_back(t += (i + " "));
});
You can try to concatinate as below using std::string + operator and iterator
std::string myCompleteString;
vector<std::string>::iterator it;
for(it=myVec.begin(); it!=myVec.end(); ++it)
myCompleteString += *it + " ";
cout << myCompleteString;
stringstream instead of repeated string concatenation, but I guess performance doesn't really matter in this case.
you can use a stringstream the exact same way as cout. Rather than printing to the screen, they will be saved in a string. The string can be accessed with .str().
See this: How to use C++ String Streams to append int?
Your code would look something like this:
vector <int> myVec;
std::stringstream ss;
for(int i=0; i<10; i++)
myVec.push_back(i); //vector holding 0-9
vector<int>::iterator it;
for(it=myVec.begin(); it!=myVec.end(); ++it) {
ss<<*it<<endl;
cout << ss.str() << " "; // prints 1 12 123 1234 ...
}
// ss.str() == "123456789";
1 12 123 1234 12345 ... 123456789?