变参数print函数的实现va_list

implement print function without print .use putchar

http://blog.csdn.net/self_chou/article/details/12858805void ;

   va_start(vp, fmt); point to current parameter ,eg: print %c\n

va_arg(vp,int) point to next parameter ,eg: c

va_end set null

----------------------------------------------------

void    print(char* fmt, ...);

void    printch(char ch);
void    printdec(int dec);
void    printflt(double flt);
void    printbin(int bin);
void    printhex(int hex);
void    printstr(char* str);
#define console_print(ch)    putchar(ch)
#include <stdio.h>
#include <stdarg.h>
//#include "print.h"
int main(void)
{
   print("print: %c\n", 'c');
   print("print %d\n", 1234567);
   print("print: %f\n", 1234567.1234567);
   print("print: %s\n", "string test");
   print("print: %b\n", 0x12345ff);
   print("print: %x\n", 0xabcdef);
   print("print: %%\n");
   return 0;
}
void    print(char* fmt, ...)
{
   double vargflt = 0;
   int  vargint = 0;
   char* vargpch = NULL;
   char vargch = 0;
   char* pfmt = NULL;
   va_list vp;
   va_start(vp, fmt);
   pfmt = fmt;
   while(*pfmt)
{
   if(*pfmt == '%')
{
   switch(*(++pfmt))
{
   case 'c':
   vargch = va_arg(vp, int); 
   /*    va_arg(ap, type), if type is narrow type (char, short, float) an error is given in strict ANSI
   mode, or a warning otherwise.In non-strict ANSI mode, 'type' is allowed to be any expression. */
   printch(vargch);
   break;
   case 'd':
   case 'i':
   //felixzh1
   vargint = va_arg(vp, int);
   printdec(vargint);
   break;
   case 'f':
   vargflt = va_arg(vp, double);
   /*    va_arg(ap, type), if type is narrow type (char, short, float) an error is given in strict ANSI
   mode, or a warning otherwise.In non-strict ANSI mode, 'type' is allowed to be any expression. */
   printflt(vargflt);
   break;
   case 's':
   vargpch = va_arg(vp, char*);
   printstr(vargpch);
   break;
   case 'b':
   case 'B':
   vargint = va_arg(vp, int);
   printbin(vargint);
   break;
   case 'x':
   case 'X':
   vargint = va_arg(vp, int);
   printhex(vargint);
   break;
   case '%':
   printch('%');
   break;
   default:
   break;
}
   pfmt++;
}
   else
{
   printch(*pfmt++);
}
}
   va_end(vp);
}
void    printch(char ch)
{
   console_print(ch);
}
void    printdec(int dec)
{
   if(dec==0)
{
   return;
}
   printdec(dec/10);
   printch( (char)(dec%10 + '0'));
}
void    printflt(double flt)
{
   int icnt = 0;
   int tmpint = 0;
   tmpint = (int)flt;
   printdec(tmpint);
   printch('.');
   flt = flt - tmpint;
   tmpint = (int)(flt * 1000000);
   printdec(tmpint);
}
void    printstr(char* str)
{
   while(*str)
{
   printch(*str++);
}
}
void    printbin(int bin)
{
   if(bin == 0)
{
   printstr("0b");
   return;
}
   printbin(bin/2);
   printch( (char)(bin%2 + '0'));
}
void    printhex(int hex)
{
   if(hex==0)
{
   printstr("0x");
   return;
}
   printhex(hex/16);
   if(hex < 10)
{
   printch((char)(hex%16 + '0'));
}
   else
{
   printch((char)(hex%16 - 10 + 'a' ));
}
}