FunctionsOnStrings.md

Functions on Strings

As a way to practice, let's define some functions that take Strings or return Strings; remember, given a String variable, say s, we can call the following methods:

• .length - returns the lenght of the String
• .substring(first, last+1) - returns a piece of the string (another string) -- numbering starts at 0
• .toLowerCase, .toUpperCase - returns the string with all upper or all lowercase
• .charAt(place) - returns the character at a given place (this is one character, not a String) -- remember numbering starts at 0
• .equals - tells if the string is equal to another

First character

We can define a function that will return the first character of a string; we can use charAt (notice this will fail if the string is empty)

public static char firstCharacter(String s)
{
    return s.charAt(0);
}

Last character

We can define a function that will return the last character of a string, by using length to get the place, and then charAt

public static char lastCharacter(String s)
{
    return s.charAt( s.length()-1 );
}

• can you try middleCharacter, which would return the character in the middle (or the lowest one, if the string has an even lenght, and so two characters in the middle).

isAllUppercase

We can use toUpperCase case to see if a string is all uppercase; if it is, it will be equal to its uppercase version

public static boolean isAllUppercase(String s)
{
    return s.equals(s.toUpperCase());
}

isAllLowercase left as exercise to the reader :)