20,175,212 Tong Haozhen "Information Security System Design Basics" Week 3 learning summary

20175212 "Information Security System Design Basics" Week 3 learning summary

Learning content summary

A familiar development environment under Linux

Second, be familiar with the basic operation of vi

Third, be familiar with the basic principles of gcc compiler

1. Format GCC [Option] [filename]
-E: compile only preprocessing
-S: converting the assembler source code C
-c: compile only, the connection is not performed
(step above normal compiler)
-o: specify the output file generated
-I: Specifies the header file directory
-I: specifies the program to link the library
-L: Specifies the name of the directory where the file library

Fourth, the skilled use of the common options gcc compiler

Fifth, skilled use gdb debugging techniques

• gdb programm (start GDB)
• b breakpoint (breakpoint to be set up four kinds: line breakpoint, the breakpoint function, conditional breakpoints, a temporary breakpoint)
• run starts running program
• bt print function call stack
• p View variable values
• c continue to run from the current breakpoint to the next breakpoint
• Single step n
• Single step s
• quit quit GDB

Sixth, be familiar with the basic principles and makefile syntax specification

Source file in a project does not count, according to its type, function modules were placed in several directories, makefile defines a set of rules to specify which files need to be compiled, which files need compiled, which files need to re compilation, even more complex functional operation, because makefile like a script, like Shell, where the operating system commands can be executed. makefile bring the benefits of that - "Automation compilation" Once written, you only need a make command, the whole project is fully automatic compiler, which greatly improves the efficiency of software development.
1.makefile

testmymath: main.o add.o sub.o mul.o div.o 
gcc main.o add.o sub.o mul.o div.o -o testmymath

2. Compile makefile, get the target file testmymath

 testmymath: main.o add.o sub.o mul.o div.o 
    gcc main.o add.o sub.o mul.o div.o -o testmymath
    main.o: main.c head.h
    gcc -c main.c
    add.o: add.c head.h
    gcc -c add.c
    sub.o: sub.c head.h
    gcc -c sub.c
    mul.o: mul.c head.h
    gcc -c mul.c
    div.o: div.c head.h
    gcc -c div.c
    
    

Seven, master generation and invoke methods of static and dynamic libraries

Eight, a C program simulation shall be understood that module, the module principle decomposition "high cohesion, low coupling"

Nine, to understand the concept of link

Textbook learning and problem-solving process

• 问题1：教材中有提到：GDB的n(next)命令让GDB执行下一行，然后暂停。 s(step)命令的作用与此类似，只是在函数调用时step命令会进入函数,那么实际使用中应该优先选用哪个？
• 问题1解决方案：经过类比以前C和Java的学习得知，应优先使用next。step 就是单步执行，遇到子函数就进入并且继续单步执行；在其他调试其中相当于step-into命令，作用是移动到下一个可执行的代码行。如果当前行是一个函数调用，则调试器进入函数并停止在函数体的第一行。step可以帮助初步揭开代码位置的谜团，例如：函数调用和函数本身可能在不同的文件中。next 是在单步执行时，在函数内遇到子函数时不会进入子函数内单步执行，而是将子函数整个执行完再停止，也就是把子函数整个作为一步。在其他调试器中相当于step-over，作用是在同一个调用栈层中移动到下一个可执行的代码行。调试器不会进入函数体。如果当前行是函数的最后一行，则，next将进入下一个栈层，并在调用函数的下一行停止

代码调试中的问题和解决过程

• 问题1：提示找不到头文件

• 问题1解决方案：之前按教材指导将head.h放在另外创建的include文件夹中，导致直接编译时无法找到。在src中拷贝一份即可编译。

  代码托管

上周考试错题总结

无

其他（感悟、思考等，可选）

xxx
xxx

学习进度条

	代码行数（新增/累积）	博客量（新增/累积）	学习时间（新增/累积）	重要成长
目标	5000行	30篇	400小时
第一周	53/53	1/1	20/20

尝试一下记录「计划学习时间」和「实际学习时间」，到期末看看能不能改进自己的计划能力。这个工作学习中很重要，也很有用。
耗时估计的公式
：Y=X+X/N ，Y=X-X/N，训练次数多了，X、Y就接近了。

参考：软件工程软件的估计为什么这么难，软件工程 估计方法

• Plan study time: XX hours

• The actual study time: XX hours

• Improvements:

(Available see more modern software engineering courseware
software engineers the ability to self-evaluation form )

Reference material

• "In-depth understanding of computer systems V3" Study Guide
• ...