printf함수 구현해보기

#include<stdio.h>
#include<stdarg.h>
int my_printf(char* str,...)
{
    int len=0;
    int i;
    char buf[256];
    va_list ap;
    va_start(ap,str);
    
    for(;*str;str++,len++)
    {
        if(*str=='%') 
        {
            switch(*(str+1))
            {
                case 'c' : //문자 
                    printf("%c",va_arg(ap,int));
                    break;
                case 's' : //문자열
                    printf("%s",ap);
                    va_arg(ap,int);
                    break;
                case 'd' : //정수 
                    printf("%d",va_arg(ap,int));
                    break;
                case 'x' : //16진수  
                    printf("%x",va_arg(ap,int));
                    break;
                case 'f' : //실수  
                    printf("%f",va_arg(ap,double));
                    break;
                default :
                    str--;
                    len--; 
                    break;
            }
            str++;
            len++;
        }
        else if(*str==92) //92는 역슬래쉬
        {
            switch(*(str+1))
            {
                case 'n' : //줄넘김 
                    printf("\n");
                    str++;
                    len++;
                    break;
                default :
                    break;
            }
        }
        else
        {
            printf("%c",*str);
        }
    }
    va_end(ap);
    return len;
}
 
int main()
{
    my_printf("  %d\n",my_printf("%d %d %c %s %c %f",1,2,'c','test','c',0.1));
    my_printf("%d %x %x %x",3);
    printf("%d",printf("asdf%d",1));
}