PHP Practice Exercise:  String Basics                

String:  a sequence of zero or more characters, enclosed within single or double
   quotation marks.

General Form:
   $stringName [ = "string value" ];
   Examples:  firstName = " LAURA\t";  lastName = 'THOMPSON\n';

String operations:  The common operators (<, >, ==) may be used with strings
   as well as concatenation (.), and functions for string manipulation including
   trimming, changing case, finding length, the position of a substring and 
   extracting a substring.

1.  The string length function -- strlen(strArg)
    this function returns the number of characters currently in a string argument.

    Find the length of firstName by invoking strlen().


2.  Trimming strings -- trim(strArg[,listOfChars])
    To strip whitespace from the start and end of a string and return the 
    resulting string.  Related functions are ltrim() and rtrim().

    Apply trim() to firstName.


3.  Changing case -- strtolower(), strtoupper(), ucfirst()
    
    Set names to lower case and capitalize the first letter of firstName and
    lastName.


4.  Concatenation (.) where a dot indicates to join two strings:
    
    Concatenate firstName to lastName and assign the result to fullName.


5.  Concatenate lastName, a comma(,), a space, and firstName with the result
    assigned to editedName.


6.  strpos(sourceString,substring[,index])
    To find the position of a substring within a source string with an optional
    index to specify where to begin the search.  This function searches the
    string for the first occurrence of a particular substring.

    Use strpos to analyze editedName for the position of the first comma (,).


7.  The substring function -- substr(strArg, start[, length]) where strArg
    is the source string, start an integer specifying the starting position,
    and optionally the length of the substring.

    Extract the lastName from the string variable editedName.


    Extract the firstName (assume it begins two positions after the comma).
    
8. The explode function -- explode($sep,$str)
   To return an array of strings separated by the string value in $sep.
   [See also, implode($sep, $stringArray) ]
 
   Explode editedName into an array with two elements.