string Objects

1
string Objects

• string is the name of a class
• Thus it is a typestring lastName
• Used in a declaration
• Creates a string object
• Initializes it to an empty string
• Other declarations(with initialization)string
  play "Hamlet"

2
string I/O

• The string class has overloaded theltlt and gtgt
  operators
• Can do I/O directly with string objectsstring
  name, prompt "Enter name "cout ltlt
  promptcin gtgt name
• string input and whitespace
• Skips leading whitespace characters
• Quits reading when whitespace encountered
• Input use getline(). (page 240-241)

3
Other string Operations

• Subscript operation
• Access individual characters of a stringstring
  name "John Doe"cout ltlt name 2
• Size method
• Determine numberof characters in the stringcout
  ltlt name.size()
• Empty method cout ltlt name.empty()
• Returns true if string is empty

4
Other string Operations

• Assignment operator
• Assign values to string objectsstring yesterday,
  today "Monday"
• Relational operator
• Elements of string operands compared character by
  character
• Out-of-bound exception

5
Other string Operations

• Concatenation
• Combining two strings into a single stringstring
  state "Michigan", greatLakegreatLake "Lake
  "state
• The substr(first, num_chars) method
• Returns a string from first for num_charscout ltlt
  greatLake.substr(2,4)

What gets printed?
6
Other string Operations

• The replace(first, num_chars, replace) method
• Replaces the contents of the replace string
  starting at first, for num_chars
• Given
• What is the end result offullname.replace(5,6,"Ey
  re")

7
Other string Operations

• The insert(position, new_string) method
• Inserts a substring into a string
• Given
• What is the result ofsignature.insert (5,"E. ")

8
Other string Operations

• The find(pattern, position) and rfind(pattern,
  position) methods
• These do pattern matching
• Searches for the specified pattern starting at
  the given position
• Returns the index of where it is found (returns
  value of stringnpos if not found)
• rfind searches from right to left
• The find_first_of(pattern, position)method
• Looks for first character from any in pattern
  starting at position

9
Problem

• Using OCD, design and implement a function that,
• Given a string containing a long-distance
  telephone number,
• Decomposes that number into its
• Area code (if the first number is a 1)
• Exchange
• Local number.

Only these two if the first number is not a 1
10
Behavior
Enter Phone number -gt 12345556789 This is a valid
number.Area code 234Exchange 555Local No.
6789