Strings

1
Strings
2
Famous Strings in History

• cheese
• g
• guitar
• shoe
• along

3
Things about Stringsthat are so interesting

• Made up of individual characters
• Denoted by double quotes
• Have invisible character at end called null
  terminator character (\0)
• How many characters in the word cat?

Answer 4 - you forgot the null terminator!!
4
Declaring Strings

• Can do multiple ways
• char charArray 255 //set size of array to 255
• char charArray blah blah blah
• // sets charArray pointing to space thats 15 big
• Both ways accomplish the same thing because both
  are pointers to memory (even though you dont
  realize it!)

5
Reading String from the User

• Use cin to get a word
• Example
• char charArray 255
• cin gtgt charArray
• Use cin.getline ( ) to get entire line of text
• Example
• cin.getline (charArray, 255)

6
BSOD

• There is a danger when getting input
• User can type a string longer than the array you
  have set up
• This will result in a crash! (trying to go into
  someone elses memory)
• Use setw( ) to solve!
• Example
• cin gtgt setw (255) gtgt charArray

Ensure input does not exceed size of array
7
Printing Strings

• Simple use cout to do this
• Example
• cout ltlt charArray ltlt endl

8
String Functions

• Whole library dedicated to strings
• include ltstring.hgt
• strcpy (char , char ) // returns a char !!!!
• strcat (char , char ) // returns a char !!!!
• strcmp (char , char ) // returns an int
• strtok (char , char ) // returns char

9
strcmp ( )

• Used to compare two strings
• CANNOT TYPE
• if (string1 string2)
• Example
• int result strcmp (Hello, World)
• // if result lt 0, then hello is lt world
• // if result 0, then hello has the same
  chars
• // if result gt 0, then hello gt world (but
  its not)

10
strtok ( )

• Token - sequence of chars separated by some
  delimiter
• Example
• When,in,the,course,of,human,events,it, becomes
• What are tokens?
• What is delimiter?

Answer the words!
Answer the comma - so we say this is a comma
delimited string of tokens
11
Usage(Pass NULL for each successive call)

• include ltiostream.hgt
• include ltstring.hgt
• void main ( )
• char charArray Jeff Rox the World
• char tokenPtr
• tokenPtr strtok (charArray, )
• while (tokenPtr !NULL)
• cout ltlt tokenPtr ltlt endl
• tokenPtr strtok (NULL, )

Notice the NULL!
Output Jeff Rox the World
12
More Code

• void main ( )
• char charArray Jeff Rox the World
• char tokenPtr
• tokenPtr strtok (charArray, e)
• while (tokenPtr !NULL)
• cout ltlt tokenPtr ltlt endl
• tokenPtr strtok (NULL, e)

Output J ff Rox th World