7.2.7 含有可变形参的参数

■ va_函数使用

■ 宏定义可变参数使用

■ 例子

#include <stdarg.h>

#include<iostream>

using namespace std;

#define D_LEN_TEXTLOG 512

void outputlog(const char *fmt, ...)

{

    char acTextBuf[D_LEN_TEXTLOG] = {0};

int i4Len = 0;

va_list valist;

va_start(valist, fmt);

i4Len = vsnprintf(acTextBuf, D_LEN_TEXTLOG, fmt, valist); 

va_end(valist);

cout << " =========================  " << endl;

cout << " len  :" << i4Len << endl;

cout << " buffer  :" << acTextBuf << endl;

}

void tVarArg(int num,...)

{

va_list argp;

va_start(argp,num); 

while(--num>=0)

printf("%s\n",va_arg(argp,char*));

va_end(argp); 

return ;

}

#define LOG_USR_STR(fmt, ...) outputlog(""fmt, ##__VA_ARGS__)

#define LOG_MY_USR_STR(fmt, ...) LOG_USR_STR(""fmt, ##__VA_ARGS__)

#define LOG_USR_STR_OTHER( ...) outputlog((char*)__VA_ARGS__)

int main() {

LOG_USR_STR("hello %d, %s", 100, "nihao");

LOG_USR_STR();

LOG_MY_USR_STR("hello %d, %s", 100, "nihao");

LOG_USR_STR_OTHER("hello %d, %s", 100, "nihao");

//LOG_USR_STR_OTHER();//失败

tVarArg(5,"Hello! ","My ","name ","is ","neverTheSame.n");

return 0;

}