STARTING OUT WITH

STARTING OUT WITH

Class 9 HonorsClass 9 Honors

2

ObjectivesObjectives

Use the string and character input/output functions

Use the character type functions in ctype.h

Understand how to use the string conversion functions to validate numeric input

3

ObjectivesObjectives

Use the C++ string class <string>

Explain the difference between strings created and used as cstrings versus string

4

Review of Pointer/Arrays/StringsReview of Pointer/Arrays/Stringschar color1[ ]=“blue”;

char * colorptr=“blue”;

char color2[5]={‘b’,’l’,’u’,’e’,’\0’};

sizeof color1 5sizeof colorptr 2sizeof color2 5

cout << color1; bluecout << colorptr; bluecout << color2; blue

5

Review of Pointer/Arrays/StringsReview of Pointer/Arrays/Stringschar color1[ ]=“blue”;char * colorptr=“blue”;char color2[5]={‘b’,’l’,’u’,’e’,’\0’};

color1[2] *colorptr *(color2+3)

colorptr[1] colorptr + 2 color2

ube

l&u&b

6

Review of Pointer/Arrays/StringsReview of Pointer/Arrays/Strings

char buffer[8]; char * ptr;

cin >> buffer;CORRECT INCORRECT

cin >> ptr;

Does buffer contain an address?

Does ptr contain an address?

Does buffer point to allocated memory for storing characters?

Does ptr point to allocated memory for storing characters?

YES NO

YES NO

7

Character TestingCharacter Testing

char Letter = ‘a’;if(isupper (Letter)) cout << “Letter is uppercase\n”;else cout << “Letter is lower case.\n”;

i<strlen (colorptr); i++)

colorptr[i] = toupper(colorptr[i]);

Table 10-1 P. 566

convert char * colorptr = “blue”to uppercase using toupper

for( int i = 0;

8

Character Testing

int main() { char Customer[8]; cout << “Enter a customer number in the form”; cout << “LLLNNNN\n”; cin.getline(Customer,8); // user enters abc1234 if (TestNum(Customer))

cout << “That’s valid”; else cout << “not the proper format”; return 0; }

P. 568 Pgrm 10-2

9

Character TestingCharacter Testingint TestNum(char CustNum[]){ for (int Count=0; Count < 3; Count++) { if (!isalpha(CustNum[Count])) return false; } for (Count =3; Count < 7; Count++)

{ if (!isdigit(CustNum[Count])) return false;} return true; }

P. 568 Pgrm 10-2

10

Character TestingCharacter Testing

int TestNum(char CustNum[]){ for (int Count=0; Count < 3; Count++) { if (!isalpha(CustNum[Count])) return false; } for (Count =3; Count < 7; Count++)

{ if (!isdigit(CustNum[Count])) return false;} return true; }

P. 568 Pgrm 10-2

11

Exercise on Validating Numeric InputExercise on Validating Numeric Input

Prompt user for a number

cout << “Enter a number\n”;

Get response into a character array

Check each character entered to see if it is a digit

char buffer[6];cin >> buffer;

for (int i=0; i < strlen (buffer); i++)

if(!isdigit(buffer[i])) { flag = 1; break; }

12

Exercise on Validating Numeric InputExercise on Validating Numeric Input

do { flag =0; cout << “Enter a number\n”;

cin >> buffer;for (int i=0; i < strlen (buffer); i + +) if ( !isdigit (buffer[i]) )

{ flag = 1; cout << “You have entered” << “an invalid number”; break;}

} while (flag = = 1);

int flag; char buffer[6];

13

atoi accepts a string and converts the string to an integer and returns that value

atof accepts a string and converts the string to a float and returns than value

int number;

number = atoi(buffer);

itoa Converts an integer to a string

14

C-String Functions from cstringC-String Functions from cstringTable 10-3

strlen accepts a pointer to a string as an argument and returns the number of characters in the string excluding the null

strcat accepts two pointers to two strings and appends the contents of the second string to the first string , altering the first string

P.579

15

C-String Functions from cstringC-String Functions from cstringTable 10-3

strcpy accepts two pointers to two strings

as arguments and copies the second string on top of the first string, replacing the first string; the null is copied onto the end of the first string

16

String Functions from cstringString Functions from cstring

Table 10-3strncpy accepts two pointers to two strings

and an integer as arguments and copies a specific number of characters from the second string on top of the first string, replacing the first string; the null is NOT copied onto the end of the first string; it is the programmers responsibility to put it there

17

String Functions from cstringString Functions from cstring

Table 10-3

strstr accepts two pointers to two strings as arguments and searches for the first occurrence of the second string in the first string; a pointer to the first character of the substring is returned; if none is found, a NULL pointer is returned

18

String Copy

cout << “enter your last name”;cin >> last;strcpy (name, last);

name

first

last

char name[13];char last [6]; char first [5];

// user enters JONES

J

J O E S

E S

\0

\0

N

O N ?? ? ? ? ? ?

19

String Concatenation

name

first

last

J

J O E S

E S

\0

\0

N

O N ?? ? ? ? ? ?

cout << name;cout << last; Displays JONES

cout << “enter your first name”;

// user enters TOMcin >> first;

T O M \0

20

String Concatenation

name

first

last

J

J O E S

E S

\0

\0

N

O N ?? ? ? ? ? ?

T O M \0

strcat (name, ”,”);

21

String Concatenation

name

first

last

J

J O E S

E S

\0N

O N ?\0 ? ? ? ? ?

T O M \0

,

strcat (name, ”,”);

strcat (name,first);

22

String Concatenation

name

first

last J O E S \0N

T O M \0

strcat (name,first);

J E SO N ,

strcat (name, ”,”);

O M \0T ?? ?

?

23

Searching for a substring inside a stringSearching for a substring inside a string

char Array[ ] = “Four score and seven years ago”;

char *StrPtr;

StrPtr = strstr(Array,”seven”);

cout << StrPtr; // displays seven years ago

24

““string” data typestring” data typestring movieTitle; // #include <string>char bookTitle[20]; // #include <cstring>

movieTitle = “Wheels of Fury”;// or cin >> movieTitle;

bookTitle = “From Here to Eternity”;

// or cin >> bookTitle;

strcpy(bookTitle,”From Here to Eternity”);

cout << movieTitle << bookTitle;

P.606-607

25

““string” data typestring” data typestring name1; // #include <string>string name2;

cout << “Enter a name (last name first):”;getline(cin,name1);cout << “Enter another name:”;getline(cin,name2);cout << “Here are the names sorted” << “alphabetically”;if (name1 < name2) cout << name1 << name2; else cout << name2 << name1;

P.609Prgm 10-15

26

““string” data type operationsstring” data type operations not available with cstring type character arrays not available with cstring type character arrays

+= Appends a copy of the stringon the right to the string object

on the left

+ Returns a string that is the concatenation of the two stringoperands

[] Implements array-subscript notation

Relational Operators < > <= >= == !=

P.611Table 10-9

27

““string” data type operationsstring” data type operations not available with cstring type character arrays not available with cstring type character arrays

string str1, str2, str3;

str1 = “ABC”;str2 = “DEF”;str3 = str1 + str2;cout << str1; // displays ABCcout << str2; // displays DEFcout << str3; // displays ABCDEFstr3 += “GHI”; cout << str3; // displays ABCDEFGHI

P.611Pgrm 10-17

28

““string” data type operations string” data type operations

string theString = “This is the time…”;

cout << theString.at(3); theString.clear();

theString = “for all good men”;

cout << theString.find(theString,’o’);

cout << theString.length();

String result = theString.substr(4,3);cout << result;

P.614Table 10-10

s

1

16

all

29

Q & A

STARTING OUT WITH

STARTING OUT WITH

Conclusion of Conclusion of Class 9Class 9