笔记
简介
《C++ Primer 中文版（第 5 版）》学习仓库，包括笔记和课后练习答案。
环境
- System:Ubuntu 16.04
- IDE:VS Code
- Compiler:g++
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：
Usage: g++ [options] file...
Options:
-pass-exit-codes Exit with highest error code from a phase
--help Display this information
--target-help Display target specific command line options
--help={common|optimizers|params|target|warnings|[^]{joined|separate|undocumented}}[,...]
Display specific types of command line options
(Use '-v --help' to display command line options of sub-processes)
--version Display compiler version information
-dumpspecs Display all of the built in spec strings
-dumpversion Display the version of the compiler
-dumpmachine Display the compiler's target processor
-print-search-dirs Display the directories in the compiler's search path
-print-libgcc-file-name Display the name of the compiler's companion library
-print-file-name=<lib> Display the full path to library <lib>
-print-prog-name=<prog> Display the full path to compiler component <prog>
-print-multiarch Display the target's normalized GNU triplet, used as
a component in the library path
-print-multi-directory Display the root directory for versions of libgcc
-print-multi-lib Display the mapping between command line options and
multiple library search directories
-print-multi-os-directory Display the relative path to OS libraries
-print-sysroot Display the target libraries directory
-print-sysroot-headers-suffix Display the sysroot suffix used to find headers
-Wa,<options> Pass comma-separated <options> on to the assembler
-Wp,<options> Pass comma-separated <options> on to the preprocessor
-Wl,<options> Pass comma-separated <options> on to the linker
-Xassembler <arg> Pass <arg> on to the assembler
-Xpreprocessor <arg> Pass <arg> on to the preprocessor
-Xlinker <arg> Pass <arg> on to the linker
-save-temps Do not delete intermediate files
-save-temps=<arg> Do not delete intermediate files
-no-canonical-prefixes Do not canonicalize paths when building relative
prefixes to other gcc components
-pipe Use pipes rather than intermediate files
-time Time the execution of each subprocess
-specs=<file> Override built-in specs with the contents of <file>
-std=<standard> Assume that the input sources are for <standard>
--sysroot=<directory> Use <directory> as the root directory for headers
and libraries
-B <directory> Add <directory> to the compiler's search paths
-v Display the programs invoked by the compiler
-### Like -v but options quoted and commands not executed
-E Preprocess only; do not compile, assemble or link
-S Compile only; do not assemble or link
-c Compile and assemble, but do not link
-o <file> Place the output into <file>
-pie Create a position independent executable
-shared Create a shared library
-x <language> Specify the language of the following input files
Permissible languages include: c c++ assembler none
'none' means revert to the default behavior of
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：
-h FILENAME, -soname FILENAME: Set internal name of shared library
-I PROGRAM, --dynamic-linker PROGRAM: Set PROGRAM as the dynamic linker to use
-l LIBNAME, --library LIBNAME: Search for library LIBNAME
-L DIRECTORY, --library-path DIRECTORY: Add DIRECTORY to library search path
获取程序状态
- 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：
#ifdef SALESITEM_H
#define SALESITEM_H
// Definition of Sales_itemclass and related functions goes here
#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*/之间的内容作为注释内容忽视。注意不能嵌套。
#define SALESITEM_H
/*
* 多行注释格式
* 每一行加一个*
*/
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
