getline() does not work if used after some inputs [duplicate]

Question

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Need help with getline()

getline() is not working, if I use it after some inputs, i.e.

#include<iostream> using namespace std;  main() { string date,time; char journal[23];   cout<<"Date:\t"; cin>>date; cout<<"Time:\t"; cin>>time;  cout<<"Journal Entry:\t"; cin.getline(journal,23);   cout<<endl; system("pause"); } 

where as if I use getline() on top of inputs, it does work i.e.

cout<<"Journal Entry:\t"; cin.getline(journal,23); cout<<"Date:\t"; cin>>date; cout<<"Time:\t"; cin>>time; 

What might be the reason?

Answer 1

Characters are extracted until either (n - 1) characters have been extracted or the delimiting character is found (which is delimiter if this parameter is specified, or '\n' otherwise). The extraction also stops if the end of the file is reached in the input sequence or if an error occurs during the input operation.

When cin.getline() reads from the input, there is a newline character left in the input stream, so it doesn't read your c-string. Use cin.ignore() before calling getline().

cout<<"Journal Entry:\t"; cin.ignore(); cin.getline(journal,23); 

Answer 2

Adding to what @DavidHammen said:

The extraction operations leave the trailing '\n' character in the stream. On the other hand, istream::getline() discards it. So when you call getline after an extraction operator, '\n' is the first character it encounters and it stops reading right there.

Put this after before getline call extraction:

cin.ignore()

A more robust way of taking input would be something like this:

while (true) {      cout<<"Time:\t";     if (cin>>time) {         cin.ignore();  // discard the trailing '\n'         break;     } else {         // ignore everything or to the first '\n', whichever comes first         cin.ignore(numeric_limits<streamsize>::max(), '\n');         cin.clear();  // clear the error flags         cout << "Invalid input, try again.\n";     } }