可变参数模拟实现printf

#include<stdio.h>
#include<stdarg.h>
#include<assert.h>
void myprintf(const char *s1, ...)
{
	assert(s1 != NULL);
	va_list arg;
	char c;
	char ch;
	char *str;
	int temp;
	va_start(arg, s1);
	while (c=*s1++)
	{
		switch (c)
		{
		case'%' :
			break;
		case 'c':
			ch = va_arg(arg,int);
			putchar(ch);
			break;
		case 's':
			str = va_arg(arg, char *);
			fputs(str, stdout);
			break;
		case 'd':
			temp = va_arg(arg, int);
			printf("%d",temp);
			break;
		default:
			putchar(c);
		}	
	}
	va_end(arg);
}
int main()
{
	char *s = "aaaaaa";
	char c = 'b';
	int i = 1997;
	myprintf("%s\n %c \n%d", s, c, i);
	system("pause");
}