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CSCI 100
Think Like Computers
Lecture 21
Fall 2008
Last Time …
•While-loop
Loops with counters
Priming the while-loop
•String as objects
Object oriented programming
Properties
Methods
String Manipulation Page Common String Methods
•useful methods exist that allow progr ammers to access
and manipulate individual components of a string
components are identifiable via indices, or numbers that
correspond to the order in which individual characters occur in a
string
indices are assigned in ascending order from left to right, so that
the first character in the string is at index 0
•the charAt method provides access to a single
character within the string
it takes an index as an input and returns the character at that
particular index
word = "foo";
ch = word.charAt(0); // ASSIGNS ch = "f"
Common String Methods
•the substring method provides access to an
entire sequence of characters within the string
it takes two numbers as inputs, representing the
starting (inclusive) and ending (exclusive) indices of
the substring, and returns the substring
•
word = "foo";
sub = word.substring(1, 3);
// ASSIGNS sub = "oo"
String Access/Concatenation
•recall: the concatenation operator (+) can join
strings together
•assuming the variable word stores a string
value, what affect would the following
assignment have?
word = word.charAt(0) +
word.substring(1, word.length);
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