靜态函數庫的建立過程:
(1)生成 *.o檔案;(2)建立靜态函數庫
[[email protected] mine]# ls add.cpp add.h main.cpp sub.cpp sub.h [[email protected] mine]# g++ -o add.o -c add.cpp [[email protected] mine]# ls add.cpp add.h add.o main.cpp sub.cpp sub.h [[email protected] mine]# g++ -o sub.o -c sub.cpp [[email protected] mine]# ls add.cpp add.h add.o main.cpp sub.cpp sub.h sub.o [[email protected] mine]# g++ -o main.o -c main.cpp [[email protected] mine]# ls add.cpp add.h add.o main.cpp main.o sub.cpp sub.h sub.o [[email protected] mine]#
其中,ar是建立靜态庫的指令, -c表示create, -r表示replace,表示當插入的子產品名已經在庫中存在就替換同名的子產品,若其中的一個子產品在庫中不存在,ar就顯示錯誤資訊,并且不替換其他同名子產品;預設情況下,新的成員增加在庫的末尾!
[[email protected] mine]# ar -cr libaddsub.a add.o sub.o [[email protected] mine]# ls add.cpp add.h add.o libaddsub.a main main.cpp main.o sub.cpp sub.h sub.o [[email protected] mine]#
此刻靜态函數庫已經建立好了,可以安全使用了,使用方法如下所示喔~:~
[[email protected] mine]# g++ -o main main.cpp -L. -laddsub
[[email protected]ocalhost mine]# ls
add.cpp add.h add.o libaddsub.a main main.cpp sub.cpp sub.h sub.o
[[email protected] mine]#
此處的-L指定靜态函數庫的位置供查找, “ .”表示在目前目錄下查找;
-l 指定靜态函數庫名, 靜态函數庫名一般為libXXX.a,其中的lib和 .a 被忽略掉;
當靜态函數庫的内容被整合進編譯後的檔案後,即是删除掉靜态函數庫,那個可執行的二進制檔案依然可以運作;如下所示:
[[email protected] mine]# ls
add.cpp add.h add.o libaddsub.a main main.cpp sub.cpp sub.h sub.o
[[email protected] mine]# ./main
a =
b =
[[email protected] mine]# rm -f libaddsub.a
[[email protected] mine]# ./main
a =
b =
[[email protected] mine]# ls
add.cpp add.h add.o main main.cpp sub.cpp sub.h sub.o
[[email protected] mine]# ./main
a =
b =
[[email protected] mine]#
動态函數庫的建立:
(1)動态連結方法
(1)g++ -shared -o libaddsub.so add.cpp sub.cpp
生成動态庫檔案libaddsub.so
(2)要先将生成的.so檔案加入到 /lib64中,因為動态函數庫被使用時,會先在/lib64下查找動态函數庫;
(3)将libaddsub.so加入到/lib64後才能生成可執行二進制檔案
g++ -o main main.cpp -laddsub
-laddsub是連接配接動态庫
[[email protected] mine]# g++ -shared -o libaddsub.so add.cpp sub.cpp
[[email protected] mine]# ls
add.cpp add.h libaddsub.so main.cpp sub.cpp sub.h
[[email protected] mine]# g++ main -o main.cpp -laddsub
g++: error: main: No such file or directory
[[email protected] mine]# ls
add.cpp add.h libaddsub.so main.cpp sub.cpp sub.h
[[email protected] mine]# g++ -o main main.cpp -laddsub
/usr/bin/ld: cannot find -laddsub
collect2: error: ld returned exit status
[[email protected] mine]# ls
add.cpp add.h libaddsub.so main.cpp sub.cpp sub.h
[[email protected] mine]# ls
add.cpp add.h libaddsub.so main.cpp sub.cpp sub.h
[[email protected] mine]# mv libaddsub.so /lib64/
Display all possibilities? (y or n)
[[email protected] mine]# mv libaddsub.so /lib64/
[[email protected] mine]# ls
add.cpp add.h main.cpp sub.cpp sub.h
[[email protected] mine]# g++ -o main main.cpp -laddsub、
/usr/bin/ld: cannot find -laddsub、
collect2: error: ld returned exit status
[[email protected] mine]# g++ -o main main.cpp -laddsub
[[email protected] mine]# ls
add.cpp add.h main main.cpp sub.cpp sub.h
[[email protected] mine]# ./main
a =
b =
[[email protected] mine]# \cp main /root/Desktop/
[[email protected] mine]#
(2)動态加載方法
以下是所有的源代碼:
//add.h
#pragma once
int add(int x, int y);
//add.cpp
#include "add.h"
int add(int x, int y)
{
return (x + y);
}
//sub.h
#pragma once
int sub(int a, int b);
//sub.cpp
#include "sub.h"
int sub(int a, int b)
{
return (a - b);
}
//main.cpp
#include <iostream>
#include "add.h"
#include "sub.h"
using namespace std;
int main()
{
int a, b;
a = add(, );
b = sub(200, 34);
cout <<"a = " << a << endl;
cout <<"b = " << b << endl;
return ;
}