1. What function can be used to determine if a specifi c character exists in a string?

strpbrk(); strops(); 

2. What is the diff erence between the str_replace() function 
and the str_ireplace() function?

both function replce a string within a string. the
difference is ireplace is case sentitve.

3. What functions are used to split a string into an indexed 
array?

str_spiit() and explode();