The most important thing about the success of the interview is its own hard power, but at the same time, complete preparation is also very necessary. Therefore, I collected some common interview questions from the Internet and prepared them early. What is the difference between
1, echo, print(), print_r()?
These three can be used for output and used during debugging.
The difference is that echo is a php statement, there is no return value, but print() and print_r() are functions, which can have a return value (print as long as the return value is 1, the error does not return a value); echo can print more Strings, because there is no return value, so the printing speed is the fastest; print can only print one string, and always returns 1; print_r can print composite type variables, such as arrays, objects, and so on.