checkout files simultaneously in perforce

In CVS we cant check out the files simultaneously. Can anybody tell ....whether in perforce can we checkout开发者_运维知识库 files simultaneously?

And i heard about locks on the files. Before merging the file do we need to have a lock on them in perforce?

If by "simultaneously" you mean "more than one person can checkout the same file in parallel". Yes, that's possible.
Regarding locks: You can lock a file (see the manual), but you don't need to.
And yes, the ones who want to submit after the first person submitted have to resolve (and possibly merge) the changes and can then submit.

Regarding locks:

• You don't need a lock on files before submitting them.
• A file can be manually locked and unlocked if you want to restrict changes from happening during a portion of time.
• A file can't be manually locked if someone else has already checked the file out (I believe), except possibly by admin override.
• You can make certain file types automatically lock when checked out (called exclusive checkout), where it makes sense to do so. For example, most binary image formats don't merge well, so those are usually made exclusive checkout to prevent two different people from modifying the image at the same time.