第一章 开始

熟悉编译器

g++：

  • 编译：g++ --std=c++11 ch01.cpp -o main
  • 运行：./prog1
  • 查看运行状态：echo $?
  • 编译多个文件:g++ ch2.cpp Sales_item.cc -o main

输入 g++ --help，查看编译器选项：

  1. Usage: g++ [options] file...
  2. Options:
  3.   -pass-exit-codes         Exit with highest error code from a phase
  4.   --help                   Display this information
  5.   --target-help            Display target specific command line options
  6.   --help={common|optimizers|params|target|warnings|[^]{joined|separate|undocumented}}[,...]
  7.                            Display specific types of command line options
  8.   (Use '-v --help' to display command line options of sub-processes)
  9.   --version                Display compiler version information
  10.   -dumpspecs               Display all of the built in spec strings
  11.   -dumpversion             Display the version of the compiler
  12.   -dumpmachine             Display the compiler's target processor
  13.   -print-search-dirs       Display the directories in the compiler's search path
  14.   -print-libgcc-file-name  Display the name of the compiler's companion library
  15.   -print-file-name=<lib>   Display the full path to library <lib>
  16.   -print-prog-name=<prog>  Display the full path to compiler component <prog>
  17.   -print-multiarch         Display the target's normalized GNU triplet, used as
  18.                            a component in the library path
  19.   -print-multi-directory   Display the root directory for versions of libgcc
  20.   -print-multi-lib         Display the mapping between command line options and
  21.                            multiple library search directories
  22.   -print-multi-os-directory Display the relative path to OS libraries
  23.   -print-sysroot           Display the target libraries directory
  24.   -print-sysroot-headers-suffix Display the sysroot suffix used to find headers
  25.   -Wa,<options>            Pass comma-separated <options> on to the assembler
  26.   -Wp,<options>            Pass comma-separated <options> on to the preprocessor
  27.   -Wl,<options>            Pass comma-separated <options> on to the linker
  28.   -Xassembler <arg>        Pass <arg> on to the assembler
  29.   -Xpreprocessor <arg>     Pass <arg> on to the preprocessor
  30.   -Xlinker <arg>           Pass <arg> on to the linker
  31.   -save-temps              Do not delete intermediate files
  32.   -save-temps=<arg>        Do not delete intermediate files
  33.   -no-canonical-prefixes   Do not canonicalize paths when building relative
  34.                            prefixes to other gcc components
  35.   -pipe                    Use pipes rather than intermediate files
  36.   -time                    Time the execution of each subprocess
  37.   -specs=<file>            Override built-in specs with the contents of <file>
  38.   -std=<standard>          Assume that the input sources are for <standard>
  39.   --sysroot=<directory>    Use <directory> as the root directory for headers
  40.                            and libraries
  41.   -B <directory>           Add <directory> to the compiler's search paths
  42.   -v                       Display the programs invoked by the compiler
  43.   -###                     Like -v but options quoted and commands not executed
  44.   -E                       Preprocess only; do not compile, assemble or link
  45.   -S                       Compile only; do not assemble or link
  46.   -c                       Compile and assemble, but do not link
  47.   -o <file>                Place the output into <file>
  48.   -pie                     Create a position independent executable
  49.   -shared                  Create a shared library
  50.   -x <language>            Specify the language of the following input files
  51.                            Permissible languages include: c c++ assembler none
  52.                            'none' means revert to the default behavior of
  53.                            guessing the language based on the file's extension

输入 g++ -v --help可以看到更完整的指令。
例如还有些常用的：

  1. -h FILENAME, -soname FILENAME: Set internal name of shared library
  2. -I PROGRAM, --dynamic-linker PROGRAM: Set PROGRAM as the dynamic linker to use
  3. -l LIBNAME, --library LIBNAME: Search for library LIBNAME
  4. -L DIRECTORY, --library-path DIRECTORY: Add DIRECTORY to library search path

获得程序状态:

  • windows: echo %ERRORLEVEL%
  • UNIX: echo $?

IO

  • #include <iostream>
  • std::cout << "hello"
  • std::cin >> v1

记住>>和<<返回的结果都是左操作数，也就是输入流和输出流本身。

endl：这是一个被称为操纵符（manipulator）的特殊值，效果是结束当前行，并将设备关联的缓冲区（buffer）中的内容刷到设备中。

UNIX和Mac下键盘输入文件结束符：ctrl+d，Windows下：ctrl+z

头文件：类的类型一般存储在头文件中，标准库的头文件使用<>，非标准库的头文件使用""。申明写在.h文件，定义实现写在.cpp文件。

避免多次包含同一头文件：

  1. #ifndef SALESITEM_H
  2. #define SALESITEM_H
  3. // Definition of Sales_itemclass and related functions goes here
  4. #endif

成员函数（类方法）：使用.调用。

命名空间（namespace）：使用作用域运算符::调用。

注释

  • 单行注释： //
  • 多行注释： /**/。编译器将/*和*/之间的内容都作为注释内容忽略。注意不能嵌套。
  1. #define SALESITEM_H
  2. /*
  3.  * 多行注释格式
  4.  * 每一行加一个*
  5.  */

while语句

循环执行，（直到条件（condition）为假。

for语句

循环头由三部分组成：

  • 一个初始化语句（init-statement）
  • 一个循环条件（condition）
  • 一个表达式（expression）

使用文件重定向

./main <infile >outfile