1. A class of system software that is designed to help the programmer discover the causes of problems found during the run-time testing in the checkout phases of the software development.Their features include the ability to stop the execut- ing program,inquire as to the state of the machine, set a breakpoint,display the arguments of an active routine,create or change a subroutine string,step the target program one statement, print the value of one or more expression,etc.
But that apparent simplicity belies Perl's rich feature set, which includes a built-in symbolic debugger and support for object oriented programming. 但这种明显的简洁性，让人看不到perl丰富的功能集，其中包括内置的符号调试程序和对面向对象编程的支持。
