1. Chapter 10 – Characters and Strings

2. 10.1 Character Testing
The C++ library provides macros for testing characters.
Be sure to include ctype.h

3. Table 10-1

4. Program 10-1
// This program demonstrates some of the character testing
// macros.
#include <iostream.h>
#include <ctype.h>
void main(void) {
char Input;
cout << "Enter any character: ";
cin.get(Input);
cout << "The character you entered is: " << Input << endl;
cout << "Its ASCII code is: " << int(Input) << endl;

5. Program continues if (isalpha(Input))
cout << "That's an alphabetic character.\n";
if (isdigit(Input))
cout << "That's a numeric digit.\n";
if (islower(Input))
cout << "The letter you entered is lowercase.\n";
if (isupper(Input))
cout << "The letter you entered is uppercase.\n";
if (isspace(Input))
cout << "That's a whitespace character.\n"; }

6. Program Output With Example Input
Enter any character: A [Enter]
The character you entered is: A
Its ASCII code is: 65
That's an alphabetic character.
The letter you entered is uppercase.
Program Output With Other Example Input
Enter any character: 7 [Enter]
The character you entered is: 7
Its ASCII code is: 55
That's a numeric digit.

7. Program 10-2
// This program tests a customer number to determine if it is
// in the proper format.
#include <iostream.h>
#include <ctype.h>
// Function prototype
int TestNum(char []);
void main(void) {
char Customer[8];
cout << "Enter a customer number in the form ";
cout << "LLLNNNN\n";
cout << "(LLL = letters and NNNN = numbers): ";
cin.getline(Customer, 8);

8. Program continues if (TestNum(Customer))
cout << "That's a valid customer number.\n";
else {
cout << "That is not the proper format of the ";
cout << "customer number.\nHere is an example:\n";
cout << " ABC1234\n"; }
// Definition of function TestNum.
int TestNum(char CustNum[])
// Test the first three characters for alphabetic letters
for (int Count = 0; Count < 3; Count++)

9. Program continues if (!isalpha(CustNum[Count])) return 0; }
// Test the last 4 characters for numeric digits
for (int Count = 3; Count < 7; Count++) {
if (!isdigit(CustNum[Count]))
return 1;

10. Program Output With Example Input
Enter a customer number in the form LLLNNNN
(LLL = letters and NNNN = numbers): RQS4567 [Enter]
That's a valid customer number.
Program Output With Other Example Input
(LLL = letters and NNNN = numbers): AX467T9 [Enter]
That is not the proper format of the customer number.
Here is an example:
ABC1234

11. 10.2 Character Case Conversion
The C++ library offers functions for converting a character to upper or lower case.
Be sure to include ctype.h

12. Table 10-2

13. Program 10-3
// This program calculates the area of a circle. It asks the user
// if he or she wishes to continue. A loop that demonstrates the
// toupper function repeats until the user enters 'y', 'Y',
// 'n', or 'N'.
#include <iostream.h>
#include <ctype.h>
void main(void) {
const float Pi = ;
float Radius;
char Go;
cout << "This program calculates the area of a circle.\n";
cout.precision(2);
cout.setf(ios::fixed);

14. Program continues do { cout << "Enter the circle's radius: ";
cin >> Radius;
cout << "The area is " << (Pi * Radius * Radius);
cout << endl;
cout << "Calculate another? (Y or N) ";
cin >> Go;
} while (toupper(Go) != 'Y' && toupper(Go) != 'N');
} while (toupper(Go) == 'Y'); }

15. Program Output With Example Input
This program calculates the area of a circle.
Enter the circle's radius: 10 [Enter]
The area is
Calculate another? (Y or N) b Enter]
Calculate another? (Y or N) y [Enter]
Enter the circle's radius: 1 [Enter]
The area is 3.14
Calculate another? (Y or N) n [Enter]

16. 10.3 Review of the Internal Storage of Strings
In C++, a sting is a sequence of characters stored in consecutive memory locations, terminated by a null character.
Figure 10-1

17. Program 10-4 // This program contains string constants
#include <iostream.h>
void main(void) {
char Again; do
cout << "C++ programming is great fun!" << endl;
cout << "Do you want to see the message again? ";
cin >> Again;
} while (Again == 'Y' || Again == 'y'); }

18. Program 10-5
// This program cycles through a character array, displaying
// each element until a null terminator is encountered.
#include <iostream.h>
void main(void) {
char Line[80];
int Count = 0;
cout << "Enter a sentence of no more than 79 characters:\n";
cin.getline(Line, 80);
cout << "The sentence you entered is:\n";
while (Line[Count] != '\0')
cout << Line[Count];
Count++; }

19. Program Output with Example Input
Enter a sentence of no more than 79 characters:
C++ is challenging but fun! [Enter]
The sentence you entered is:
C++ is challenging but fun!

20. 10.4 Library Functions for Working with Strings
The C++ library has numerous functions for handling string.s These functions perform various tests and manipulations.
Functions discussed in this section require the inclusion of string.h

21. Figure 10-2

22. Table 10-3

23. Program 10-6
// This program uses the strstr function to search an array
// of strings for a name.
#include <iostream.h>
#include <string.h> // For strstr
void main(void) {
char Prods[5][27] = {"TV inch Television",
"CD257 CD Player",
"TA677 Answering Machine",
"CS109 Car Stereo",
"PC955 Personal Computer"};
char LookUp[27], *StrPtr = NULL;
int Index;

24. Program continues cout << "\tProduct Database\n\n";
cout << "Enter a product number to search for: ";
cin.getline(LookUp, 27);
for (Index = 0; Index < 5; Index++) {
StrPtr = strstr(Prods[Index], LookUp);
if (StrPtr != NULL)
break; }
if (StrPtr == NULL)
cout << "No matching product was found.\n";
else
cout << Prods[Index] << endl;

25. Program Output With Example Input
Product Database
Enter a product to search for: CD257 [Enter]
CD257 CD Player
Program Output With Example Input
Enter a product to search for: CS [Enter]
CS109 Car Stereo
Program Output With Other Example Input
Enter a product to search for: AB [Enter]
No matching product was found.

26. 10.5 String/Numeric Conversion Functions
The C++ library provides functions for converting a string representation of a number to a numeric data type, and vice-versa.
The functions in this section require the stdlib.h file to be included.

27. Table 10-4

28. Program 10-7
// This program demonstrates the strcmp and atoi functions.
#include <iostream.h>
#include <string.h> // For strcmp
#include <stdlib.h> // For atoi
void main(void) {
char Input[20];
int Total = 0, Count = 0;
float Average;
cout << "This program will average a series of numbers.\n";
cout << "Enter the first number or Q to quit: ";
cin.getline(Input, 20);

29. Program continues
while ((strcmp(Input, "Q") != 0)&&(strcmp(Input, "q") != 0)) {
Total += atoi(Input); // Keep a running total
Count++; // Keep track of how many numbers entered
cout << "Enter the next number or Q to quit: ";
cin.getline(Input, 20); }
if (Count != 0)
Average = Total / Count;
cout << "Average: " << Average << endl;

30. Program Output With Example Input
This program will average a series of numbers.
Enter the first number or Q to quit: 74 [Enter]
Enter the next number or Q to quit: 98 [Enter]
Enter the next number or Q to quit: 23 [Enter]
Enter the next number or Q to quit: 54 [Enter]
Enter the next number or Q to quit: Q [Enter]
Average: 62

31. 10.6 Focus on Software Engineering: Writing Your Own String-Handling Functions
You can design your own specialized functions for manipulating strings.

32. Program 10-8
// This program uses a function to copy a string into an array.
#include <iostream.h>
void StringCopy(char [], char []); // Function prototype
void main(void) {
char First[30], Second[30];
cout << "Enter a string with no more than 29 characters:\n";
cin.getline(First, 30);
StringCopy(First, Second);
cout << "The string you entered is:\n" << Second << endl; }

33. Program continues void StringCopy(char String1[], char String2[]) {
int Index = 0;
while (String1[Index] != '\0')
String2[Index] = String1[Index];
Index++; }
String2[Index] = '\0';

34. Program Output With Example Input
Enter a string with no more than 29 characters:
Thank goodness it’s Friday! [Enter]
The string you entered is:
Thank goodness it's Friday!

35. Program 10-9
// This program uses the function NameSlice to "cut" the last
// name off of a string that contains the user's first and
// last names.
#include <iostream.h>
void NameSlice(char []); // Function prototype
void main(void) {
char Name[41];
cout << "Enter your first and last names, separated ";
cout << "by a space:\n";
cin.getline(Name, 41);
NameSlice(Name);
cout << "Your first name is: " << Name << endl; }

36. Program continues
// Definition of function NameSlice. This function accepts a
// character array as its argument. It scans the array looking
// for a space. When it finds one, it replaces it with a null
// terminator.
void NameSlice(char UserName[]) {
int Count = 0;
while (UserName[Count] != ' ' && UserName[Count] != '\0')
Count++;
if (UserName[Count] == ' ')
UserName[Count] = '\0'; }

37. Program Output With Example Input
Enter your first and last names, separated by a space:
Jimmy Jones [Enter]
Your first name is: Jimmy

38. Figure 10-3

39. Figure 10-4

40. Program 10-10
// This program demonstrates a function, CountChars, that counts
// the number of times a specific character appears in a string.
#include <iostream.h>
// Function prototype
int CountChars(char *, char);
void main(void) {
char UserString[51], Letter;
cout << "Enter a string (up to 50 characters): ";
cin.getline(UserString, 51);
cout << "Enter a character and I will tell you how many\n";
cout << "times it appears in the string: ";
cin >> Letter;
cout << Letter << " appears ";
cout << CountChars(UserString, Letter) << " times.\n"; }

41. Program continues
// Definition of CountChars. The parameter StrPtr is a pointer
// that points to a string. The parameter Ch is a character that
// the function searches for in the string. The function returns
// the number of times the character appears in the string.
int CountChars(char *StrPtr, char Ch) {
int Times = 0;
while (*StrPtr != '\0')
if (*StrPtr == Ch)
Times++;
StrPtr++; }
return Times;

42. Program Output With Example Input
Enter a string (up to 50 characters):Starting Out With C++ [Enter]
Enter a character and I will tell you how many
times it appears in the string: t [Enter]
t appears 4 times.