#include<stdio.h>
#include<conio.h>
void main()
{
int a;
void scanchar(char**);
int scans(char**,char*,int,int);
int scani(char**,int,int,int,int,int,int);
int myscanf(char *);
int smyscanf(char*,char*);
clrscr();
printf("enter");
myscanf("%d",&a);
printf("%d",a);
getch();
}
static void scanchar(char **str)
{
 extern int getchar();
 if (str) {
  **str = getchar();
  ++(*str);
 }
 else (void)getchar();
}
#define PAD_RIGHT 1
#define PAD_ZERO 2
static int prints(char **in, const char *string, int width, int pad)
{
 register int sc = 0, padchar = ' ';
 if (width > 0) {
  register int len = 0;
  register const char *ptr;
  for (ptr = string; *ptr; ++ptr) ++len;
  if (len >= width) width = 0;
  else width -= len;
  if (pad & PAD_ZERO) padchar = '0';
 }
 if (!(pad & PAD_RIGHT)) {
  for ( ; width > 0; --width) {
   scanchar (in, padchar);
   ++sc;
  }
 }
 for ( ; *string ; ++string) {
  scanchar (in, *string);
  ++sc;
 }
 for ( ; width > 0; --width) {
  scanchar (in, padchar);
  ++sc;
 }
 return sc;
}
/* the following should be enough for 32 bit int */
#define SCAN_BUF_LEN 12
static int scani(char **in, int i, int b, int sg, int width, int pad, int letbase)
{
 char scan_buf[SCAN_BUF_LEN];
 register char *s;
 register int t, neg = 0, sc = 0;
 register unsigned int u = i;
 if (i == 0) {
  scan_buf[0] = '0';
  scan_buf[1] = '\0';
  return scans (out, print_buf, width, pad);
 }
 if (sg && b == 10 && i < 0) {
  neg = 1;
  u = -i;
 }
 s = scan_buf + SCAN_BUF_LEN-1;
 *s = '\0';
 while (u) {
  t = u % b;
  if( t >= 10 )
   t += letbase - '0' - 10;
  *--s = t + '0';
  u /= b;
 }
 if (neg) {
  if( width && (pad & PAD_ZERO) ) {
   scanchar (in,'-');
   ++sc;
   --width;
  }
  else {
   *--s = '-';
  }
 }
 return sc + scans (in, s, width, pad);
}
static int scan(char **in, int *varg)
{
 register int width, pad;
 register int sc = 0;
 register char *format = (char *)(*varg++);
 char scr[2];
 for (; *format != 0; ++format) {
  if (*format == '%') {
   ++format;
   width = pad = 0;
   if (*format == '\0') break;
   if (*format == '%') goto in;
   if (*format == '-') {
    ++format;
    pad = PAD_RIGHT;
   }
   while (*format == '0') {
    ++format;
    pad |= PAD_ZERO;
   }
   for ( ; *format >= '0' && *format <= '9'; ++format) {
    width *= 10;
    width += *format - '0';
   }
   if( *format == 's' ) {
    register char *s = *((char **)varg++);
    sc += scans (in, s?s:"(null)", width, pad);
    continue;
   }
   if( *format == 'd' ) {
    sc += scani (in, *varg++, 10, 1, width, pad, 'a');
    continue;
   }
   if( *format == 'x' ) {
    sc += scani (in, *varg++, 16, 0, width, pad, 'a');
    continue;
   }
   if( *format == 'X' ) {
    sc += scani (in, *varg++, 16, 0, width, pad, 'A');
    continue;
   }
   if( *format == 'u' ) {
    sc += scani (in, *varg++, 10, 0, width, pad, 'a');
    continue;
   }
   if( *format == 'c' ) {
    /* char are converted to int then pushed on the stack */
    scr[0] = *varg++;
    scr[1] = '\0';
    sc += scans (in, scr, width, pad);
    continue;
   }
  }
  else {
  in:
   scanchar (in, *format);
   ++sc;
  }
 }
 if (in) **in = '\0';
 return sc;
}
/* assuming sizeof(void *) == sizeof(int) */
int myscanf(const char *format, ...)
{
 register int *varg = (int *)(&format);
 return scan(0, varg);
}
int smyscanf(char *out, const char *format, ...)
{
 register int *varg = (int *)(&format);
 return scan(&out, varg);
}

#include <ctype.h>
#include <stdio.h>
#include <stdarg.h>
 
int myscanf ( const char *fmt, ... );
static int trim_leading ( void );
static int myscanf_internal ( const char *fmt, va_list args );
 
int main ( void )
{
  char s[100];
  int a;
 
  myscanf ( "%s%d", s, &a );
  printf ( "%s\n%d\n", s, a );
 
  return 0;
}
 
int myscanf ( const char *fmt, ... )
{
  va_list args;
  int rv;
 
  va_start ( args, fmt );
  rv = myscanf_internal ( fmt, args );
  va_end ( args );
 
  return rv;
}
 
static int trim_leading ( void )
{
  int ch;
 
  do {
    if ( ( ch = getchar() ) == EOF )
      break;
  } while ( isspace ( ch ) );
 
  ungetc ( ch, stdin );
 
  return ch;
}
 
static int myscanf_internal ( const char *fmt, va_list args )
{
  int converted = 0;
 
  while ( *fmt != '\0' ) {
    if ( *fmt++ == '%' ) {
      switch ( *fmt ) {
      case 's':
        {
          char *dst = va_arg ( args, char* );
          int ch;
 
          trim_leading();
 
          while ( ( ch = getchar() ) != EOF && !isspace ( ch ) )
            *dst++ = (char)ch;
          *dst = '\0';
 
          ++converted;
        }
        break;
      case 'd':
        {
          int neg = 0;
          int dst = 0;
          int ch;
          int i;
 
          trim_leading();
 
          for ( i = 0; ( ch = getchar() ) != EOF; i++ ) {
            if ( i == 0 && ( ch == '-' || ch == '+' ) ) {
              neg = ( ch == '-' );
              continue;
            }
 
            if ( !isdigit ( ch ) ) {
              ungetc ( ch, stdin );
              break;
            }
 
            dst = 10 * dst + ( ch - '0' );
          }
 
          if ( neg )
            dst = -dst;
 
          *va_arg ( args, int* ) = dst;
          ++converted;
        }
        break;
      }
    }
  }
 
  return converted;
}