局部变量可以与全局变量同名，在函数内引用这个变量时，会用到同名的局部变量，而不会用到全局变量。对于有些编译器而言，在同一个函数内可以定义多个同名的局部变量，比如在两个循环体内都定义一个同名的局部变量，而那个局部变量的作用域就在那个循环体内。 -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.