一个有趣的c++案例

 1. 源码

#include <stdio.h>
#include <stdint.h>
#include <iostream>

using namespace std;

uint8_t a = 0;
uint8_t b = 0;

#define MY_LOG

#ifdef MY_LOG

#define my_log(...)   printf(__VA_ARGS__); fflush(stdout)

#else
#define my_log(...)   
#endif


void printf_info(){cout<<endl;fflush(stdout);}

template <typename T, typename... Types >
void printf_info(const T first_arg, Types&... other)
{
    cout << first_arg;
    printf_info(other...);
    fflush(stdout);
}

int main(int argn, char* argv[])
{
    my_log("a:%d, b:%d\n",a, b);
    int aa = (int)a;
    int bb = (int)b;
    printf_info("a:",aa, "  b:", bb);
    a = b + 1;
    b = 1;
    return 0;
}

2.Makefile

TGT := app
OPTION := -I.
SRC = reorder_demo.cpp

all:$(TGT)
	@echo "Make successfull!"

$(TGT):$(SRC)
	g++ -std=c++11 $(OPTION) $^ -o $@

clean:
    ifneq ( ,$(TGT))
		@rm $(TGT)
    else
		@echo "no fi
		e exist, nothing to do"
    endif

.PHONY: all clean

3. 结果

xuehy@ubuntu:~/code/cpp_demo$ ./app 
a:0, b:0
a:0  b:0

4. 后记

一切好处尽在不言中，蕴含知识点如下如下

• log的重定义
• 变数参数函数
• makefile中删除对象