numberconverter.cpp

这是一个简单的进位制转换程序

#*******************************************************
#     MYCPLUS Sample Code - http://www.mycplus.com     *
#                                                     *
#   This code is made available as a service to our   *
#      visitors and is provided strictly for the      *
#               purpose of illustration.              *
#                                                     *
# Please direct all inquiries to saqib at mycplus.com *
#******************************************************/

#include <iostream.h>
#include <conio.h>
#include <string.h>
#include <math.h>

int Validate(char[], int, int);     // returns if a valid number was typed in
void ConvToDec(char[], int, int, int);    // changes original number into a decimal
void EvaluateWhole(long, int);
void EvaluateFract(double, int);

const int MAXSTRING = 30 ;

void main()
{
  char old_string[MAXSTRING];
  int original_base, new_base ;

  clrscr();
  cout << "\nPlease enter the number you would like to convert"
		 << " (max-30 characters): " ;
  cin.getline(old_string, MAXSTRING, '\n') ;
  cout << "\nPlease enter the base you were writing in(eg.2-binary): " ;
  cin >> original_base ;

  if (!Validate(old_string, original_base, strlen(old_string)))
	 cout << "\nThe number you entered did not match with the base you specified!" ;
  else
  {
	 cout << "\nPlease enter the base you want to convert to: " ;
	 cin >> new_base ;
	 ConvToDec(old_string, original_base, new_base, strlen(old_string));
  }
  getch();
}//Begin

int Validate(char str[], int base, int length)
{
  int aski_val ;

  aski_val = '0' + base ;
  if (base>10)
	 aski_val += ('A' - '9') -1;      // Adjust so 'A' comes immediately after 9

  for (int i=0; i<length; i++)
  {
	 if (str[i] >= aski_val)
		return 0;     // invalid
  }
  return 1;   // valid
}//Validate

void ConvToDec(char str[], int base, int new_base, int length)
{
  double dec_frac =0;
  long dec_num =0;
  int dec_digit =0;

  for (int i=0; i<length && str[i]!='.'; i++)
  {
	 dec_digit = str[i] - '0';
	 if (str[i]>='A')
		dec_digit -= ('A' - '9') -1;   // Adjust so 'A' comes immediately after 9
	 dec_num = dec_digit + dec_num*base;
  }

  EvaluateWhole(dec_num, new_base);

  int index;

  if (str[i] == '.')
  {
	 for (index = --length ; index > i; index--)
	 {
		dec_digit = str[index] - '0';
		if (str[index]>='A')
		  dec_digit -= ('A' -'9') -1;  // Adjust so 'A' comes immediately after 9
		dec_frac = (dec_frac + dec_digit)/base;
	 }
	 EvaluateFract(dec_frac, new_base);
  }
}//ConvToDec

void EvaluateWhole(long DecWhole, int base)
{
  char new_string[MAXSTRING] ;
  int i = 0, aski_val;

  while (DecWhole > 0)
  {
	 aski_val = DecWhole % base + '0';
	 if (DecWhole%base > 9)
		aski_val += ('A' - '9') -1;   // Adjust so 'A' comes immediately after 9
	 new_string[i] = aski_val ;
	 DecWhole = DecWhole/base ;
	 i++;
  }

  cout << "\nThe number converted is " ;
  for (int j=i-1; j>=0; j--)
	 cout << new_string[j] ;
}//Evaluate

void EvaluateFract(double DecFrac, int base)
{
  char FracDigit ;  // 4 places
  int Digit ;

  cout << "." ;    // decimal point
  for (int i=0; i<10; i++)    // 6 decimal places
  {
	 DecFrac = DecFrac * base ;    // Bring out digit after point
	 Digit = DecFrac ;
	 DecFrac -= Digit;

	 FracDigit =  Digit + '0' ;
	 if (base>10 && FracDigit>'9')
		FracDigit += ('A' - '9' - 1) ;
	 cout << FracDigit ;
  }
}