// Version 1
while (cin.get(ch)) // quit on eof
{
if (ch == ' ')
spaces++;
if (ch == '\n')
newlines++;
}
// Version 2
while (cin.get(ch)) // quit on eof
{
if (ch == ' ')
spaces++;
else if (ch == '\n')
newlines++;
}
What advantages, if any, does the second form have over the first?
2. In Listing 6.2, what is the effect of replacing ++ch with ch+1?
3. Carefully consider the following program:
#include
using namespace std;
int main()
{
char ch;
int ct1, ct2;
ct1 = ct2 = 0;
while ((ch = cin.get()) != '$')
{
cout << ch;
ct1++;
if (ch = '$')
ct2++;
cout << ch;
}
cout <<"ct1 = " << ct1 << ", ct2 = " << ct2 << "\n";
return 0;
}
Suppose you provide the following input, pressing the Enter key at the end of each line:
Hi!
Send $10 or $20 now!
What is the output? (Recall that input is buffered.)
4. Construct logical expressions to represent the following conditions:
a. weight is greater than or equal to 115 but less than 125.
b. ch is q or Q.
c. x is even but is not 26.
d. x is even but is not a multiple of 26.
e. donation is in the range 1,000–2,000 or guest is 1.
f. ch is a lowercase letter or an uppercase letter. (Assume, as is true for ASCII, that lowercase letters are coded sequentially and that uppercase letters are coded sequentially but that there is a gap in the code between uppercase and lowercase.)
5. In English, the statement “I will not not speak” means the same as “I will speak.” In C++, is !!x the same as x?
6. Construct a conditional expression that is equal to the absolute value of a variable. That is, if a variable x is positive, the value of the expression is just x, but if x is negative, the value of the expression is -x, which is positive.
7. Rewrite the following fragment using switch:
if (ch == 'A')
a_grade++;
else if (ch == 'B')
b_grade++;
else if (ch == 'C')
c_grade++;
else if (ch == 'D')
d_grade++;
else
f_grade++;
8. In Listing 6.10, what advantage would there be in using character labels, such as a and c, instead of numbers for the menu choices and switch cases? (Hint: Think about what happens if the user types q in either case and what happens if the user types 5 in either case.)
9. Consider the following code fragment:
int line = 0;
char ch;
while (cin.get(ch))
{
if (ch == 'Q')
break;
if (ch != '\n')
continue;
line++;
}
Rewrite this code without using break or continue.
Programming Exercises
1. Write a program that reads keyboard input to the @ symbol and that echoes the input except for digits, converting each uppercase character to lowercase, and vice versa. (Don’t forget the cctype family.)
2. Write a program that reads up to 10 donation values into an array of double. (Or, if you prefer, use an array template object.) The program should terminate input on non-numeric input. It should report the average of the numbers and also report how many numbers in the array are larger than the average.
3. Write a precursor to a menu-driven program. The program should display a menu offering four choices, each labeled with a letter. If the user responds with a letter other than one of the four valid choices, the program should prompt the user to enter a valid response until the user complies. Then the program should use a switch to select a simple action based on the user’s selection. A program run could look something like this:
Please enter one of the following choices:
c) carnivore p) pianist
t) tree g) game
f
Please enter a c, p, t, or g: q
Please enter a c, p, t, or g: t
A maple is a tree.
4. When you join the Benevolent Order of Programmers, you can be known at BOP meetings by your real name, your job title, or your secret BOP name. Write a program that can list members by real name, by job title, by secret name, or by a member’s preference. Base the program on the following structure:
// Benevolent Order of Programmers name structure
struct bop {
char fullname[strsize]; // real name
char title[strsize]; // job title
char bopname[strsize]; // secret BOP name
int preference; // 0 = fullname, 1 = title, 2 = bopname
};
In the program, create a small array of such structures and initialize it to suitable values. Have the program run a loop that lets the user select from different alternatives:
a. display by name b. display by title
c. display by bopname d. display by preference
q. quit
Note that “display by preference” does not mean display the preference member; it means display the member corresponding to the preference number. For instance, if preference is 1, choice d would display the programmer’s job title. A sample run may look something like the following:
Benevolent Order of Programmers Report
a. display by name b. display by title
c. display by bopname d. display by preference
q. quit
Enter your choice: a
Wimp Macho
Raki Rhodes
Celia Laiter
Hoppy Hipman
Pat Hand
Next choice: d
Wimp Macho
Junior Programmer
MIPS
Analyst Trainee
LOOPY
Next choice: q
Bye!
5. The Kingdom of Neutronia, where the unit of currency is the tvarp, has the following income tax code:
First 5,000 tvarps: 0% tax
