3 (6pts) Answer the following questions and write code where indicated.

1. How do you pass a variable by reference?

2. How to know if a variable is set?

3. Under which circumstance can you use the control structure for to loop over an array in PHP without missing any values?

4. Function to check if a variable is empty?

5. Write a script to format these values in money currency style when added. Sample values: val2 = 12.895, val1 = 45.896

6. Write a PHP script to return the part of the string from the starting of the string up to a specific value in the string. Ex. rayy@example.com should return rayy when @ is use as the value.