Single or Double Quotes?

Should you use single or double quotes in your code?

Sometimes people use double quotes in PHP to avoid having to use the period to separate code. For example, you could write:

"I have a $color shirt on today";

Faster however is not always better. A better way to write this code would be:

'I have a ' .$color. ' shirt on today';

Phrasing your code in the second method will result in less chance of error messages, or problems with other programmers deciphering your code.