Summary of C-language method of mixed compilation under C + +

Recently read SGI STL source code, feel the learning of C + + is very helpful, before the generic, iterator, traits and so on various characteristics of the concept is very vague, through the two days of pondering, coupled with the "STL Source Analysis" help, to C + + that weird grammar is no longer afraid.

Some of the problems encountered in it are summarized as follows:

1. C + + blank base class optimization (EBO)

Reference: http://www.xuebuyuan.com/1610977.html

If there is an empty class, the following. The space occupied is not 0byte, but usually 1 byte.

Class a{};

If there is a class, the following. While a accounts for 1 byte, while int accounts for 4bytes, the class occupies 8bytes due to the alignment of the compiler.

Class B {public:  A;  int x;    }

and Class C, as follows. Because the space base class is optimized for 4, the compiler automatically optimizes if there is no data in the inherited Class (1 bytes in space).

Class C:public a{public:int x;};

2. C C + + compile-language functions

In C + + in the implementation of the new function, its underlying is still using the C language of malloc, the implementation of the following ideas (see: http://songpengfei.iteye.com/blog/1100239).

Files Test_extern_c.h and Test_extern_c.c define a function thisistest ()

File:test_extern_c.h

#ifndef __test_extern_c_h__
#define __test_extern_c_h__

#ifdef __cplusplus

extern "C" {

#endif

extern int thisistest (int a,int b);

#ifdef __cplusplus
}

#endif

#endif

And the function is implemented as follows:

#include "test_extern_c.h" int thisistest (int a,int b) {return a * b;}

The main.cpp call is as follows:

#include "test_extern_c.h" #include "stdio.h" #include "Stdlib.h" Class Foo{public:int bar (int a,int b) {printf ("result=% I\n ", Thisistest (A, b));}; int main (int argc,char **argv) {int a = Atoi (argv[1]); int b = atoi (argv[2]); Foo *foo = new Foo (); Foo->bar (A, B); return (0);}

The Mac GCC compiles as follows:

Gcc-c TEST_EXTERN_C.C//generated the target file

A target file can be generated by the following command.

g++ main.cpp TEST_EXTERN_C.O

3. Implementation mechanism of New/delete in C + + language

4. Mixed programming of assembly language in C + +

Summary of C-language method of mixed compilation under C + +