CODEWITHSUNDEEP
c++setifstream
Cameron
Cameron

Reputation: 661

istream_iterator read values from file into set

I am having difficulty using the istream_iterator for the purpose I need. I have a file that I want to read line by line into a set. I have to use the iterator and I was wondering if there's something wrong with my code or my approach.

The help is much appreciated. Here's a simplified version of the code I'm writing:

main.cpp

#include <iostream>
#include <fstream>
#include <string>
#include <set>

using namespace std;

int main() {

    ifstream file("fruits.txt");

    set<string> M;

    copy(istream_iterator<string>(file),
         istream_iterator<string>(),
         [](string & s){ M.insert(s); });

    for( auto val : M ) {
        cout << val << ", ";
    }

    return 0;
}

fruits.txt

banana
apple
pear
strawberry
blueberry
peach
pear
apple

Errors:

main.cpp:16:26: Variable 'M' cannot be implicitly
captured in a lambda with no capture-default specified


/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr
/include/c++/v1/algorithm:1750:49: Cannot increment value of type '(lambda at 
/Users/cnapoli22/Downloads/TEST SHIT/TEST SHIT/main.cpp:16:10)'

Upvotes: 1

Views: 4506

Answers (1)

Simple
Simple

Reputation: 14390

The last argument to copy needs to be an iterator, not a lambda:

#include <algorithm>
#include <fstream>
#include <iostream>
#include <iterator>
#include <set>
#include <string>

using namespace std;

int main()
{
    ifstream file("fruits.txt");

    set<string> M;

    copy(istream_iterator<string>(file),
         istream_iterator<string>(),
         inserter(M, M.end()));

    for (auto const& val : M)
    {
        cout << val << ", ";
    }
}

Upvotes: 4

Related Questions