• do myfile.pm unconditionally loads in and evaluates a file. require myfile.pm does it only if it hasn't been done already
• You must use a file name with do. You can use either a file name or a module name with require.
• Only require can be used to insist on a specific version of Perl
• do can be used to group multiple statements into a single expression.require can't. For example,
  • do {...} foreach ...
  • do {....} while {...}
  • eval {...} or do {...}

For more information, please see require and do.

Best, beth

require checks if the file was already executed. do EXPR doesn't.

The makes require the better choice when loading a module (a file with a package directive), and do otherwise (i.e. never).

do also has an unrelated do BLOCK form which is useful for inlining multiple statements into an expression.

quoth do's pod: ... inclusion of library modules is better done with the use and require operators, which also do automatic error checking and raise an exception if there's a problem.

The differences aren't huge, but if you read do and require, you will see differences.

I think the require will also use "do File" inside it. Am I right?

Well, it might do - I have no idea.

What affect would it have on you if you knew the answer to that question?

--
use JAPH;
print JAPH::asString();