Sams Teach Yourself C++ in 21 Days

Working with Streams 601

17

must have enough room in the buffer to allow for the entire string plus the null. The null

signals the “end of string” to the cinobject.

String Problems ..............................................................................................

After all this success with cin, you might be surprised when you try to enter a full name

into a string. cinhas trouble getting the full name because it believes that any white-

space is a separator. When it sees a space or a new line, it assumes the input for the para-

meter is complete, and in the case of strings, it adds a null character right then and there.

Listing 17.2 illustrates this problem.

LISTING17.2 Trying to Write More Than One Word to cin

0: //Listing 17.2 - character strings and cin

1:

2: #include <iostream>

3:

4: int main()

5: {

6: char YourName[50];

7: std::cout << “Your first name: “;

8: std::cin >> YourName;

9: std::cout << “Here it is: “ << YourName << std::endl;

10: std::cout << “Your entire name: “;

11: std::cin >> YourName;

12: std::cout << “Here it is: “ << YourName << std::endl;

13: return 0;

14: }

Your first name: Jesse

Here it is: Jesse

Your entire name: Jesse Liberty

Here it is: Jesse

On line 6, a character array called YourNameis created to hold the user’s input.

On line 7, the user is prompted to enter one name, and that name is stored prop-

erly, as shown in the output.

On line 10, the user is again prompted, this time for a full name. cinreads the input, and

when it sees the space between the names, it puts a null character after the first word and

terminates input. This is not exactly what was intended.

To understand why this works this way, examine Listing 17.3, which shows input for

several fields.

OUTPUT

ANALYSIS