Perl Study Notes No. 4

1. ChildProgram(In common ?), It starts with "&" in a call to distinguish it from "$" and @
2. the scalar in the subroutine block is global without any modification. This subroutine is called multiple times in a file and can be modified multiple times.
3. The value of the expression calculated in the last step in the subroutine will be used as the return value... (the real TM is a lazy person)
4. The parameter list of the subroutine is provided only when it is called !!! Save in @ _
5. Use the my statement in the subroutine to create private variables, such as Sub max {My ($ M, $ n) =@_; $ m> $ n? $ M: $ N ;}
6. Variables cannot be repeatedly defined in the same scope.
7. When you call a subroutine, add & to avoid conflict with embedded functions.
8. $ # array is only the subscript of the last element. The actual number must be + 1 !!
9. Pop and shift cannot specify elements...
10. Use <> to read the file... it's too late...
11. printf () is similar to C, but the parameters change. the output number is usually % G, which can automatically identify the type of number used; % s is a string; % d is a decimal integer, % x sixteen, % o eight ;...