Taking strings with spaces as input and storing into class data member.

[yomama]

Hello,

I am writing a program in which I take a string (specifically, first and last name with a space in between) from the user and put it into a data member of a class node. I have tried various things, but to no avail.

I am using using Borland Turbo C++ 2005 on XP Professional SP2.

My includes for both methods:

#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <stdlib>
using namespace std;
 

This first method compiles OK, but does not wait for user input, and skips right to the next line...

void CEmployee::AddEmp()    //user defined class and member function
{
   CEmployee *pCurr;
   std::string name;
 
//m_Name, m_Age, and m_pHead are CEmployee data members
   pCurr = new CEmployee;
   pCurr->m_pLink = m_pHead;
   m_pHead = pCurr;
 
   cout << "Enter Employee Name: ";
   cin.getline(pCurr->m_Name, 20, '\n');
 
   cout << "Enter Employee's Age: ";
   cin >> pCurr->m_Age;
 
 //rest of program follows

This compiles fine, but the output is wrong; the program does not wait for user input before moving on to [cout << "Enter Employee's Age: ";]. Nor does it put [cout << "Enter Employee's Age: ";] onto a new line (as I would expect).

Output:

Enter Employee Name: Enter Employee's Age: [waits for input here]

I also tried the following (based on advice I saw in another post regarding spaces in strings), and it wouldn't even compile:

void CEmployee::AddEmp() 
{
   CEmployee *pCurr;
   std::string name;
 
   pCurr = new CEmployee;
   pCurr->m_pLink = m_pHead;
   m_pHead = pCurr;
 
   cout << "Enter Employee Name: ";
   std::getline(std::cin, name, 20, '\n');
   pCurr->m_Name = name;      
 
   cout << "Enter Employee's Age: ";
   cin >> pCurr->m_Age;
 
//rest of program follows
 
 

This generated two compiler errors:
1) Could not find a match for 'std::getline<_Elem,_Traits,_Alloc>(istream, string, int, char)

This error is obviously in reference to [std::getline(std::cin, name, 20, '\n')]

2) Lvalue required

This is in reference to <pCurr->m_Name = name;>

Please help. I am having a hell of a time figuring this out!
Thanks in advance.

[weaknessforcats]

The first thing the >> operator does is to check to see of the input stream in in a fail state. If it is, it just returns without doing anything so your program just races on like there were no cin >> statement inthe code.

Nowhere do I see to check to see of the >> failed:

 
cin >> something
if (cin.fail() )
{
    //oops...
}
 

You need to check every cin >>.

If you are in a fail state, then cin.clear() will reset the failbit but the offending data will still be in the input stream. You will need to flush the stream or extract data using means other than the >> operator to clear the bad data.

[yomama]

The first thing the >> operator does is to check to see of the input stream in in a fail state. If it is, it just returns without doing anything so your program just races on like there were no cin >> statement inthe code.

Nowhere do I see to check to see of the >> failed:

Code: ( cpp )

cin >> something
if (cin.fail() )
{
//oops...
}



You need to check every cin >>.

If you are in a fail state, then cin.clear() will reset the failbit but the offending data will still be in the input stream. You will need to flush the stream or extract data using means other than the >> operator to clear the bad data.

Thanks for the reply.
Note that the problem I'm having in the first scenario is at line 12:

cin.getline(pCurr->m_Name, 20, '\n');

This is the line at which that C++ fails to wait, and here i do not explicitly call >> with cin. Does getline() implicitly call >> ?

For what it's worth, I tried sticking the following after line 12:

   if (cin.fail())
        cout << "cin failed, bro.";
 

C++ did not print that statement, and skipped to the next line, this time with a '\n'

Output:
Employee Name:
Employee Age: [waits for input here]

It's also worth mentioning that today with the same code I was using last night (and without the cin.fail check), my program did wait for input at line 12, but then barfed when I entered a string (either with or without a space). It acted just like it would if I entered a char when it as expecting an int.

Not sure what is going on here...

[Laharl]

Try using >> to fix your problem with getline(). To fix the error with spaces, use quotes (" ") to surround your whole string, as items on the input stream are delimited by any form of whitespace.

For example:

string name;
cout << "Enter name: ";
cin >> name;
cout << name;
 

Sample output:
Enter name: Joe Jones
Joe

Enter name: "Joe Jones"
Joe Jones

[yomama]

Try using >> to fix your problem with getline(). To fix the error with spaces, use quotes (" ") to surround your whole string, as items on the input stream are delimited by any form of whitespace.

For example:
Code: ( cpp )

1.
string name;
2.
cout << "Enter name: ";
3.
cin >> name;
4.
cout << name;



Sample output:
Enter name: Joe Jones
Joe

Enter name: "Joe Jones"
Joe Jones

Doing that allows line 12 to stop for input (as expected), but doesn't take the whole string. My debugger shows that the first ", J, o, and e, are assigned to the first four elements of my array. Then the fifth element points to 0. The following three elements are assigned t, x, 2, and point to some random memory addressed. Every remaining element of my array thereafter points to NULL.

The remaining characters from the cin (i.e. , J, o, n, e, s, and ") are then stuck in the buffer, and cause my program to go into what appears to be an inifinite loop, while it tries to figure out what to do with them.

[Laharl]

Hrm, you're right. I guess you do have to use getline(). Look up strtok() if you need specific parts of the input line.

[yomama]

Hrm, you're right. I guess you do have to use getline(). Look up strtok() if you need specific parts of the input line.

Thanks. I'll make learning more about strtok() my next order of business. My current understanding of strtok(), though, is that it is used to stop reading input at a certain point (e.g. some delimiter) rather than to continue reading input at a certain point (which is what I want to do here), but I'll investigate it some more once this pesky work day is up.

[Studlyami]

when you first call strtok you tell where to start looking and what your looking for. Then on the second call you pass NULL in for the location and it will continue where it left off from the last call.

[yomama]

Got it figured out, everyone. I had an enter press stuck in the buffer from a previously called function that I needed to discard. Once I did that, cin.getline() worked like a charm.

Thanks for the help!