First Undefined Variable then Undefined offset
7250
Reference - What does this error mean in PHP?
42204
Effect of declared and undeclared variables
110212
Assign same value to multiple variables at once?
59380
Get first key in a (possibly) associative array?
25703
Best way to test for a variable's existence in PHP; isset() is clearly broken
116533
Why is there an offset in the Java String implementation?
1340
What are "sequence points" and how do they affect undefined behavior?
103160
Is there a PHP function for swapping the values of two variables?
105287
(Why) is using an uninitialized variable undefined behavior?
70947
DEFINE vs Variable in PHP
157501
How do I set variables for variable_get()?
153624
What's the difference between is_null($var) and ($var === null)?
30680
Post-increment on a dereferenced pointer?
30914
Unbound variable and name
14596
Are PHP Variables passed by value or by reference?
76704
Undefined variable: $_SESSION
5123
PHP variable variables