C and pointer Chapter 18 runtime environment 18.7 problems

1. In your environment , What does the stack frame look like ？ 
analysis ：
Leave it to be proved later . 
2. In your system , How many characters can a meaningful external identifier have ？ 
analysis ：
Leave it to be proved later . 
3. In your environment , How many variables can a register store ？ For pointer and non pointer values , Does it make a distinction ？ 
analysis ：
Leave it to be proved later . 
4. In your environment , How parameters are passed to functions ？ How values are returned from functions ？ 
analysis ：
Leave it to be proved later . 
5. On the machine used in this chapter , If a function declares one or more of its parameters as register variables , Then the parameters of this function are pushed onto the stack in the function order as usual , Then copy it to the correct register . If these parameters can be saved directly to the register , Functions will be more efficient . Can this parameter passing technique be realized ？ If you can , How to achieve it ？
analysis ：
This is a good idea , But it cannot be achieved . In the prototype of the function ,register Keywords are optional , Therefore, there is no reliable way to call a function to know which parameters （ If any ） It is declared like this . 
6. In the environment we are discussing , The calling function is responsible for clearing the parameters it pushes into the stack . that , Can the called function complete this task ？ If not , So under what conditions can it ？
analysis ：
It's impossible . Only the calling function knows how many parameters are actually pushed onto the stack . however , If you push a parameter counter into the stack , The called function can clear all parameters . however , It first needs to pop up the return address and save . 
7. If assembly language is better than C More efficient procedures , So why not write all the programs in assembly language ？
analysis ：
Here's why ：

1. Poor portability .
2. Write the difficult . 
3. Developing large projects is inefficient . 

/* This feeling sounds abstract , I haven't studied before , Write after learning .*/