Thread: New line help

How about using the string class member function? I.e.

Code:

if (!buffer.empty()) {
    // update your field
}

I dont think operator!=() is defined for the string class, so maybe your buffer != "" is comparing the address of buffer with the address of the literal "", which are not the same.

Ok, I threw that in. Now it seems to be skipping something, in the wrong way.

After I enter in what record to update, it should display the first entry in that record to update. However, it is displaying the 1st entry, then the 2nd entry, then allowing input from the user. I have to type in two entries and press enter in order for it to move on. When it moves on it displays the 3rd entry but simply skips over it entirely, not allowing me to input anything for it.

So the output looks like (in relation to the program above), bold is user input:

Code:

Enter a new str1 value: Enter a new str2 value:  <enter>
<enter>
Enter a new str3 value:

Then it will kick out of the function without allowing me to enter anything for that 3rd entry. So it looks like my buffer is getting filled with something.. Either way the entire function is still not updating anything, no matter what I enter.

Maybe related to the fact that getline(...) will leave the newline character on the stream. So the next time you call getline(...) it finds the "\n" and returns right away. Try adding cin.ignore() after each call to getline(...).

Originally Posted by Mr Moe

I'm looking for a way to detect if just the new line character was entered in and nothing else. To do this I had a string named "buffer" that was initialized to empty. At each of the 3 instances to input, I did a getline( cin , buffer ). Then I checked if( buffer != "" ), then execute what I need to (or in other words update the information).

Again this code doesn't seem to work for me; it is just a simple example. Any help would be appreciated, thanks.

If your code implements what you are describing, it should work.

Here is a complete example. Tell me if it doesn't work for you. Also tell what compiler/operating system you are using. It should report empty strings as well as anything else you enter on any given line. (It should keep asking for strings until you tell it to quit.)

Code:

#include <iostream>
#include <string>

using std::cin;
using std::cout;
using std::endl;
using std::flush;
using std::string;

int main()
{
  string str1, str2, str3;

  while (1) {
    cout << "Enter str1: " << flush;
    getline(cin, str1);
    if (str1 == "") {
      cout << "You entered a newline (only) for str1" << endl;
    }
    else {
      cout << endl << "You entered str1 <" << str1 << ">" << endl << endl;
    }
    if (str1 == "quit") {
      break;
    }

    cout << "Enter str2: " << flush;
    getline(cin, str2);
    if (str2 == "") {
      cout << "You entered a newline (only) for str2" << endl;
    }
    else {
      cout << endl << "You entered str2 <" << str2 << ">" << endl << endl;
    }
    if (str2 == "quit") {
      break;
    }

    cout << "Enter str3: " << flush;
    getline(cin, str3);
    if (str3 == "") {
      cout << "You entered a newline (only) for str3" << endl;
    }
    else {
      cout << endl << "You entered str3 <" << str3 << ">" << endl << endl;
    }
    if (str3 == "quit") {
      break;
    }
  }

  return 0;
}

[edit] getline() works wonderfully well by itself. Comparing strings with "" works wonderfully well. The problems that people usually have is when they use cin>> and getline() alternately. If you have some cin>> integer or cin>> character stuff between the calls to getline(), then you will have to empty the input buffer.
[/edit]

Regards,

Dave