CODEWITHSUNDEEP
c++vector
psrag anvesh
psrag anvesh

Reputation: 1275

How to take values for two different vectors?

vector<int> a;
vector<int> b;

int temp_holder;

cout << "\n Give the first ints \n" ;
while (cin >> temp_holder)
    a.push_back(temp_holder);

cout << "\n Give the second ints \n";
while (cin >> temp_holder)
    b.push_back(temp_holder);

When i press ctrl + z for the first while loop the second also automatically ends. What is happening and how to fix it and is this the most efficient way to take values into a vector using while(cin >> var);
Thank you!

Upvotes: 1

Views: 82

Answers (3)

R Sahu
R Sahu

Reputation: 206717

Your strategy is flawed.

The first while loop will end only when there is no more input or there is an error in the input.

You can rely on the error to break the loop, clear the error state of the stream, ignore the rest of the line, and then continue to read the elements of the second vector in the second while loop.

cout << "\n Give the first ints \n" ;
while (cin >> temp_holder)
   a.push_back(temp_holder);

// If EOF is reached, there is nothing more to read.
if ( cin.eof() )
{
   // Deal with EOF.
}

// Clear the error state.
cin.clear();

// Ignore the rest of the line.
cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

// Continue to read the elements of the second vector.
cout << "\n Give the second ints \n";
while (cin >> temp_holder)
   b.push_back(temp_holder);

Using this approach, you can use 

1 2 3 4 5 
xxxx
10 20 30 40 50

as your input. The numbers before xxxx will be read and stored in the first vector while those after xxxx will be read and stored in the second vector.

Upvotes: 0

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

When i press ctrl + z for the first while loop the second also automatically ends.

CTRL+Z invalidates the cin stream state (being at eof). Thus any further calls like

cout << "\n Give the second ints \n";
while (cin >> temp_holder)
    b.push_back(temp_holder);

will fail.

You could use std::getline() to get the first and second set of integer value separately. This requires to enter a white space separated set of numbers, and let the user press the ENTER key to indicate the whole set is entered.

Then you can use std::istringstream to extract the numbers to the vectors as needed.

Upvotes: 0

Vlad from Moscow
Vlad from Moscow

Reputation: 311088

Use 

std::cin.clear();

between the loops.

Upvotes: 2

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