Thread: assignment of new string

i need to figure out a way to make the resulting 4 digit number assigned into a new string... any help would be appreciated...
also, i can't get this while statement to work??? i suck at C++!!!!

Code:

#include <iostream.h>
#include <stdlib.h>
#include <iomanip>
#include <string.h>

int main()

{
bool valid = false;
char initialdigit [5];
int x;
int tmp;
int firstinteger;

 cout<<"Please enter a non-zero 4 digit number..."<<endl;
 cin>> initialdigit;

 firstinteger = atoi (initialdigit);

 if (firstinteger > 0)
    valid = true;

 while (valid)
    {
     if (initialdigit [0] < initialdigit [1])
       {
         tmp = initialdigit [0];
         initialdigit [0] = initialdigit [1];
         initialdigit [1] = tmp;
        }
    if (initialdigit [1] < initialdigit [2])
        {
          tmp = initialdigit [1];
          initialdigit [1] = initialdigit [2];
          initialdigit [2] = tmp;
        }
    if (initialdigit [2] < initialdigit [3])
       {
          tmp = initialdigit [2];
          initialdigit [2] = initialdigit [3];
          initialdigit [3] = tmp;
        }

         }
valid = false;

cout<<firstinteger<<endl;


      system("PAUSE");
      return 0;
}

thanks guys...

i think my main problem here is getting the compiler to arrange the 4 digit number into descending order and then storing that string into a character... after i do that, i'll be gravy... SOMEONE HELP!!! I CAN'T FIND ANYTHING ANYWHERE ON ARRANGING CHARACTERS WITHIN A STRING....

I change some statements, when input '1234', output is '2341',
not correct, how to decrease 'if' code?

Code:

#include <iostream>
#include <stdlib.h>
#include <iomanip>
#include <cstring>
using namespace std;

int main()
{
bool valid = false;
char initialdigit [5];
int x;
int tmp;
int firstinteger;

 cout<<"Please enter a non-zero 4 digit number..."<<endl;
 cin>> initialdigit;

 firstinteger = atoi (initialdigit);

 if (firstinteger > 0)
    valid = true;

 while (valid)
    {
     if (initialdigit [0] < initialdigit [1])
       {
         tmp = initialdigit [0];
         initialdigit [0] = initialdigit [1];
         initialdigit [1] = tmp;
        }
    if (initialdigit [1] < initialdigit [2])
        {
          tmp = initialdigit [1];
          initialdigit [1] = initialdigit [2];
          initialdigit [2] = tmp;
        }
    if (initialdigit [2] < initialdigit [3])
       {
          tmp = initialdigit [2];
          initialdigit [2] = initialdigit [3];
          initialdigit [3] = tmp;
        }

         
    valid = false;
     }

//cout<<firstinteger<<endl;
cout<<initialdigit [0]<<initialdigit [1]
    <<initialdigit [2]<<initialdigit [3]<<endl;

      system("PAUSE");
      return 0;
}

toysoldier: if you want to learn what's wrong with your code review what happens with the while() loop. Since valid is assigned false after the first time through the loop, the loop will stop after sorting just the first value. You need to keep going after the first element is sorted somehow. To use the swap technique like you have it, probably the easiest way is to use two loops that are nested. The outer loop will keep track of how many times to do a series of comparisons. The inner loop will keep track of which comparison you are doing. The ifs can be reduced to just one comparison that is an abstract comparison rather than a hard coded comparison like you use. In general, this technique is called a basic bubble sort. There are lots of variations that can be used to optimize the basic version, so develop/use one that you can understand. There are a number of posts about bubble sorts on the board and I'm sure you can find lots of references by "googling" as well.

Of course, as hk_mp5kpdw idicated, you can always use the generic sort from the STL algorhithm header file if this isn't some form of homework and you just want something that works whether you understand it or not.

I think It may help you:
- There are a big difference between number and number in character.
- There are a big difference between string terminated by zero and a character.

Code:

//sort number
//mybe algorithm is Bubble Sort
//a bruce force algorithm
//optimized for check input buffer
#include <iostream>
using namespace std;
//convert from a character to a number
int chartoint(char c)
	{
		char buffer[2];
		buffer[1]=0;//string need to be terminated by ZERO
		buffer[0]=c;
		return atoi(buffer);
	}
//use to swap
void c_swap(char &a, char &b)
	{
		char buffer;
		buffer=a;
		a=b;
		b=buffer;
	}
//check "number" is number or not
bool checknumberstring(char*s)
	{

		int l = strlen(s);
		for (int i=0; i<l+1;i++)
				if (s[i]<'0' && s[i]>'9')
					return false;
		return true;
	}
//main here

#define	NUMBER	10

int main()

	{
	char initialdigit [NUMBER];
	unsigned int firstinteger;
	cout<<"Please enter a non-zero digit number..."<<endl;
	fgets(initialdigit, NUMBER, stdin);

// check input data here

	if (strlen(initialdigit)!=NUMBER-1 || checknumberstring(initialdigit)==false) 
		{
			cout << "Error! Input..." << endl;
			system("PAUSE");
			return 1;
		}
	firstinteger = atoi (initialdigit);
	if (firstinteger > 0)
		{
		for (int i=0; i<NUMBER-1; i++)
			for (int j=0; j<NUMBER-1; j++)
				if (chartoint(initialdigit [j]) < chartoint(initialdigit [j+1]))
					c_swap(initialdigit [j], initialdigit [j+1]);
		}
	cout<<initialdigit<<endl;
	system("PAUSE");
	return 0;
	}