Challenges solution : MyPrint()

Here is my solution for MyPrint().

#include <stdio.h>
#include <conio.h>
#include <stdarg.h>
void print_int_hex(int val,int alg)
{
 int i;
 if (val==0)
 {
  _putch('0');
 }
 else
 {
  if (val/alg)
  {
   i = val % alg;
   print_int_hex(val/alg,alg);
  }
  else
   i = val % alg;
  if (i>9)
  {
   i=i-10+'a';
   _putch(i);
  }
  else
   _putch(i?i+48:48);
 }
}

void print_float(double val)
{
 int temp = val *100;

 if (val==0)
 {
  _putch('0');
 }
 else
 {
  print_int_hex(temp/100,10);
  _putch('.');
  print_int_hex(temp%100,10);  
 }
}

void MyPrint(char* pString,...)
{
 int i=0;
 int ch;
 const char* str;
 double f;
 
    va_list args;
    va_start(args, pString);
 while (pString[i])
 {
  if (pString[i]=='%')
  {
   i++;
   switch(pString[i])
   {
   case 'c':
    ch = va_arg(args, int);
    _putch(ch);
    break;
   case 's':
    str = va_arg(args, const char*);
    _cputs(str);
    break;
   case 'd':
    ch = va_arg(args,int);
    if (ch<0)
    {
     _putch('-');
     ch=ch*(-1);
    }
    print_int_hex(ch,10);
    break;
   case 'x':
   case 'X':
    ch = va_arg(args, int);
    print_int_hex(ch,16);
    break;
   case 'f':
    f = va_arg(args, double);
    print_float(f);
    break;
   }
   i++;
  }
  _putch(pString[i]);
  i++;  
 }
    va_end(args);
}

int main()
{
 MyPrint("int %d, char %c, string %s, hex %x, float %f", -102, 'A', "hello", 31, 12.34567);
 return 0;
} 

Result as:
int -102, char A, string hello, hex 1f, float 12.34
For float, I thought might be have better solution.

Optimizing bio_display()

Here is the source code:

void bio_display(const char *str, int row, int col, int len){
  bio_move(row, col);
  if(len <= 0){
    bio_putstr(str);
  }
  else{
    int i;
    for(i=0; i< len && str[i];i++){
      bio_putch(str[i]);
    }
    for(;i< len;i++){
      bio_putch(' ');
    }
  }
}

To optimize it, I got this solution :

void bio_display(const char *str, int row, int col, int len) {
    bio_move(row, col);
    if( len <= 0)
        bio_putstr(str);
    else {
        for(;len>0; len--) bio_putch(*str ? *str++ : ' ' );
    }
}

From the same logic, it also can be shortened as:

void bio_display(const char *str, int row, int col, int len) {
   for((bio_move(row, col), (len <= 0)?bio_putstr(str):0);  len>0;   len--)
       bio_putch(*str ? *str++ : ' ' );
} 

I tried to use bio_putstr() instead of bio_putch() which Farad mentioned in the class, but considered the length of the string I insisted to use bio_putch().