C++之调用C的so(七十六)

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C++之调用C的so(七十六)

1.代码示例  

1.编译C的so库
# emacs add.h
extern "C" { int add(int a, int b);
}//如果去掉：extern "C",会有如下报错：
对‘add(int, int)’未定义的引用# emacs add.c
#include <stdio.h>
int add(int a, int b){printf("a = %d, b = %d\n",a,b);return a + b;
}# gcc -shared -fPIC -o libadd_c.so add.c2.C++调用C的so库 
# emacs test.cpp
#include <stdio.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <iostream>
#include "add.h"using namespace std;int main(){int a = 0;a = add(3, 4);return 0;
}注意：如果不加: #include "add.h"，
会如下报错：
test.cpp:11:7: error: ‘add’ was not declared in this scope# g++ test.cpp -L ./ -ladd_c -o test# export LD_PRELOAD="./libadd_c.so"
# ./test
a = 3, b = 4