C + + programming under Linux--development environment construction and first program

Previous article Linux C + + programming--Introduction we have introduced the gun, GCC, g++ and other important concepts, should now start hands-on practice!

Installation of development tools

Environment
Distributions version: CentOS 6.7
Linux kernel slices: 2.6.32-573.3.1.el6.i686

After installing the General Linux installation by default (GNU Compiler Collection), you can check the GCC and g++ version numbers to see if GCC and g++ are installed.

[luowf @luoweifu  ~]$  GCC-VGCC version 4.4 . 7  20120313  (Red  hat  4.4 . 7 -16 ) (GCC  ) [Luowf @luoweifu  ~]$  g++-VGCC version 4.4 . 7  20120313  (Red  hat  4.4 . 7 -16 ) (GCC  ) 

If it is not installed, you can install the development toolset with the following command when the Linux system is linked to the network:

"Development Tools"

First HelloWorld Program

When it comes to programs, the first one is definitely helloworld, so let's start with HelloWorld, write a simple Hello program, and compile and run.

Write the first program

[LUOWF@luoweifucplusplus]$pwd/home/luowf/Workspace/cplusplus//write the first HelloWorld program in Vim[LUOWF@luoweifucplusplus]$ Vim HelloWorld.cpp1#include <iostream>2 3 intMain ()4{5Std::cout <<"Hello wolrd!"<< Std::endl;6         return 0;7}//Compile program[LUOWF@luoweifucplusplus]$ g++ HelloWorld.cpp [LUOWF@luoweifucplusplus]$lsA.out HelloWorld.cpp test1 TEST2[LUOWF@luoweifucplusplus]$./a.out Hello wolrd! [LUOWF@luoweifucplusplus]$

The difference between g++ and GCC

In the previous article, we have actually introduced GCC and g++, saying that GCC is a C compiler, and g++ is a C + + compiler. Does that mean that GCC compiles only C, and g++ only compiles C + +? In fact, GCC can also compile C + + programs, and C + + is a C based on the development, so g++ can not compile C language. The differences between them are as follows:
1. The suffix is. C, GCC treats it as a C program, and g++ as a C + + program; the suffix is. cpp, both of which are considered C + + programs. Note that while C + + is a superset of C, there are differences in the requirements for syntax, and the syntax rules for C + + are more rigorous.
2. During the compile phase, g++ calls GCC, which is equivalent to C + + code, but because the GCC command is not automatically linked to the libraries used by C + + programs, it is usually done with g++ to complete the link, for the sake of unification, simply compile/link all with g++, which gives an illusion, As if the CPP program can only be used g++. Compile with GCC, add the libraries you want to link to in the options, or compile C + +. As the HelloWorld program above, we can also compile with the following command:

[luowf@luoweifuCplusplus]$ HelloWorld.cpp[luowf@luoweifuCplusplus]$ lsa.out  HelloWorld.cpp  test1  test2[luowf@luoweifuCplusplus]$ HelloWolrd![luowf@luoweifuCplusplus]$ 

1. GCC does not define __cplusplus macros, and g++ will
   This macro simply indicates that the compiler will interpret the code in C or C + + syntax, as described above, if the suffix is. c, and the GCC compiler is used, the macro is undefined, otherwise it is defined.

Reference article: http://www.linuxsky.org/doc/dev/200804/298.html

Compilation of programs and common commands

Compile the source code into a target file without linking

gcc -c HelloWorld.cpp

Optimized execution speed According to the operating system at compile time

-O HelloWorld.-c

Link the target file into two (executable) files

-o HelloWorld HelloWorld.-lstdc++

HelloWorld is the executable file name, HELLOWORLD.O is the target file name, and if the C source file of the. c suffix is not added-lstdc++, if it is a C + + source file with a. cpp suffix, add-lstdc++.

When making a binary file, fill in the linked function library with the associated path

(.cpp文件)gcc -lstdc++ HelloWorld.cpp

Or

(.c文件)gcc HelloWorld.-lm-L-I /usr/include

Description
-LM refers to the libm.so or LIBM.A function library file;
The path followed by-L is the search directory for the function library just above;
-I is the directory where the include file (which contains the MATH.H header file) is located in the source code.

The HelloWorld.cpp code is as follows:

  1 #include <iostream>  2 #include <math.h>  3   4 intMain ()5{6         STD::cout<<"Hello wolrd!"<<STD:: Endl;7         floatValue =Sin(3.14/2);8         STD::cout<<"Value:"<< value <<STD:: Endl;9         return 0;Ten}

Outputs the results of a compiled link to a specific file name

-lstdc++-o HelloWorld HelloWorld.cpphelloWorld为输出的文件名   

At compile time, output more information to explain

-lstdc++-o HelloWorld HelloWorld.-Wall

C + + programming under Linux--development environment construction and first program