my_fprintf.c

int my_fprintf(FILE* fp, char* str, ...)
{
 
  va_list arg;
  char *y;
  int i, len = 0;
  char *atr;
  int num;
  char arr[100];
  char arrprint[100];

  va_start(arg, str);

  y = str;

 while(*y != 0)
    {
  if(*y == '%')
  {
   switch (*(++y))
   {
   case 's':
    atr = va_arg(arg, char*);
    if(atr != NULL)
    {
     for(i=0; atr[i] != '\0'; i++)
     {
      arrprint[len++]=atr[i];
     }
   
     break;
    }
   case 'd':
    num = va_arg(arg, int);
    for(i=0; num>0; i++)
    {
     arr[i] = (num%10) + '0';
     num/=10;
    }
    for(; i>0;)
    {
     arrprint[len++] = arr[--i];
    }
    break;

   case 'c':
    arrprint[len++] = va_arg(arg, char);
    break;

   }
  }
  else
  {
   arrprint[len++] = *y;
  }
  y++;

 }
 va_end(arg);

 arrprint[len] = '\0';

 fputs(arrprint, fp);

 return len;

}

my_printf.c

int my_printf(char* str, ...)
{
  va_list arg;
  char *y;
  int i, len = 0;
  char *atr;
  int num;
  char arr[100];
  char arrprint[100];

  va_start(arg, str);

  y = str;

 while(*y != 0)
    {
  if(*y == '%')
  {
   switch (*(++y))
   {
   case 's':
    atr = va_arg(arg, char*);
    if(atr != NULL)
    {
     for(i=0; atr[i] != '\0'; i++)
     {
      arrprint[len++]=atr[i];
     }
   
     break;
    }
   case 'd':
    num = va_arg(arg, int);
    for(i=0; num>0; i++)
    {
     arr[i] = (num%10) + '0';
     num/=10;
    }
    for(; i>0;)
    {
     arrprint[len++] = arr[--i];
    }
    break;

   case 'c':
    arrprint[len++] = va_arg(arg, char);
    break;

   }
  }
  else
  {
   arrprint[len++] = *y;
  }
  y++;

 }
 va_end(arg);

 arrprint[len] = '\0';

 for(i=0;i<len;i++)
  putchar(arrprint[i]);

 return len;
}

my_sprintf.c

int my_sprintf(char* Dststr,char* str, ...)
{
  va_list arg;
  char *y;
  int i, len = 0;
  char *atr;
  int num;
  char arr[100];
  char arrprint[100];

  va_start(arg, str);

  y = str;

 while(*y != 0)
    {
  if(*y == '%')
  {
   switch (*(++y))
   {
   case 's':
    atr = va_arg(arg, char*);
    if(atr != NULL)
    {
     for(i=0; atr[i] != '\0'; i++)
     {
      arrprint[len++]=atr[i];
     }
   
     break;
    }
   case 'd':
    num = va_arg(arg, int);
    for(i=0; num>0; i++)
    {
     arr[i] = (num%10) + '0';
     num/=10;
    }
    for(; i>0;)
    {
     arrprint[len++] = arr[--i];
    }
    break;

   case 'c':
    arrprint[len++] = va_arg(arg, char);
    break;

   }
  }
  else
  {
   arrprint[len++] = *y;
  }
  y++;

 }
 va_end(arg);

 arrprint[len] = '\0';

 *Dststr = puts(arrprint);

 return len;
}