Hmm... Don't know of any tutorials about specific characters. But, by far the most useful site for me is php.net. I'll give you a little info though.
The quotemark characters (" and ') are used to define a string, either when defining a value or when used for comparisson.
$strVar = "This is a string"; OR
$strVar = 'This is a string';
Both uses are valid. Where some of your confusion might be coming from is the use of quotes within a string. For example what if you wanted the string to be Let's go. Well, you can't just use single quotes, as above, to define the string like this:
$strVar = 'Let's go'; //(incorrect)
The problem with this is that the second single quote mark (in let's) would be interpreted as the end of the string! The remainder of the line s go' would try to be interpreted and would result in a parsing error. There are two solutions. The first is to use double quotes to define your string:
$strVar = "Let's go";
That way the single quote is interpreted as part of the string. You could also escape the inner single quote like this:
$strVar = 'Let\'s go';
By using the \ before the single quote you are telling the interpreter to treat the next character as a literal character rather than a programming construct. For example if you needed to include the \ character in a string you would have to use two of them (\\).
As a last example, if you wanted a string to be set to He said, "Let's go." you could write it like this:
$strVar = "He said, \"Let's go\""; OR
$strVar = 'He said, "Let\'s go"';
Michael J
