(A-1) shows that string input

• Can be tricky

Example of (A-1)

// instr1.cpp -- reading more than one string
#include <iostream>
int main()
{
	using namespace std;
	const int ArSize = 20;
	char name[ArSize];
	char dessert[ArSize];
 
	cout << "Enter your name:\n";
	cin >> name;
	cout << "Enter your favorite dessert:\n";
	cin >> dessert;
	cout << "I have some delicious " << dessert;
	cout << " for you, " << name << ".\n";
	return 0;
}

The intent of the program in (A-1) is simple:

• Read a user’s name and favorite dessert from the keyboard and then display the information (B-1)

Here is a sample run (A-1):

Program Notes (A-1)

• (B-1) We didn’t even get a chance to respond to the dessert prompt (B-2)
  • (B-2) The program showed it and then immediately moved on to display the final line (B-3)

• (B-3) The problem lies with how cin determines when you’ve finished entering a string (B-4)
• (B-4) You can’t enter the null character from the keyboard (B-5)
• (B-5) cin needs some other means for locating the end of a string (B-6)
• (B-6) The cin technique (B-7)
• (B-7) Is to use whitespace—spaces, tabs, and newlines—to delineate a string (B-8)
• (B-8) This means cin reads just one word when it gets input for a character array (B-9)
• (B-9) After it reads this word, cin automatically adds the terminating null character when it places the string into the array (B-10)

• (B-10) The practical result in this example (B-11)
  • (B-11) Is that cin reads Bjarne as the entire first string and puts it into the name array (B-12)
    • (B-12) This leaves poor Stroustrup still sitting in the input queue (B-13)
    • (B-13) When cin searches the input queue for the response to the favorite dessert question, it finds Stroustrup still there (B-14)
    • (B-14) Then cin gobbles up Stroustrup and puts it into the dessert array (Image-1)

(Image-1) The cin view of string input

Another problem, which didn’t surface in the sample run

• Is that the input string might turn out to be longer than the destination array
• Using cin as this example did offer no protection against placing a 30-character string in a 20-character array