Introduction - If you have any usage issues, please Google them yourself
Local variables and global variables of the same name, a reference to the variable in the function, it will use the local variables of the same name, but does not use global variables. For some compilers, in the same function can define multiple local variables of the same name, such as define local variables of the same name in both the loop body, and the scope of the local variables in the body of the loop.