dividing a string into substrings with three elements in C++

lindaonline15 · 06-23-2011, 10:17 AM

hi,

im trying to receive a string from user, then divide it into groups of strings with 3 elements only.
meaning if input is:
12345 it should give 123 and 45
123456 it should give 123 and 456
1234567 it should give 123 and 456 and 7

anyway what happens based on my code is that it works fine with first two (when it has groups of 3 elements and 2 element, and also when it has groups of all 3 elements) but for the last case (when makes groups of 3 elements and 1 group of 1 element) it shouws as "123 456 7 D"!! meaning it adds one extra character to the last element out of no where!

can anyone tell me what is the problem with my code??

here is my code:

Code:

#include <iostream>
#include <conio>
struct array
{
	char first;
	char second;
	char third;
};
int main ()
{
while(1){
	const int SIZE=256;
	int size=0;
	bool done=0;
	char num[SIZE],arr[3];
	int i=0,j=1,k=2;
	int z=0,x=0;
   array *arrPtr;
	cin>>num;
	for (int i=0;!done && i<SIZE;i++)
		if (num[i]!='\0')
			size++;
		else done=1;
   z=size/3;
	cout<<"Size is: "<<size<<endl;
	if(size%3==0)
   {
   	arrPtr=new array[z];
     	for(int x=0;x<z;i=i+3,j=j+3,k=k+3,x++)
			{
				arrPtr[x].first=num[i];
      	   arrPtr[x].second=num[j];
         	arrPtr[x].third=num[k];
			}
      for(int x=0;x<z;i=i+3,j=j+3,k=k+3,x++)
			{
      		cout<<arrPtr[x].first<<arrPtr[x].second;
	      	cout<<arrPtr[x].third<<endl;
			}
   }
   else
   {
   	z++;
      arrPtr=new array[z];
    	for(int x=0;x<z;i=i+3,j=j+3,k=k+3,x++)
			{
				arrPtr[x].first=num[i];
      	   arrPtr[x].second=num[j];
         	arrPtr[x].third=num[k];
			}
		x--;
      if((size%3)==1)
      	{
         	arrPtr[x].second=' ';
         	arrPtr[x].third=' ';
         for(x=0;x<z;x++)
				{
      			cout<<arrPtr[x].first<<arrPtr[x].second;
		      	cout<<arrPtr[x].third<<endl;
				}
         }
      else
      	{
            arrPtr[x].third=' ';
            for(x=0;x<z;x++)
					{
      				cout<<arrPtr[x].first<<arrPtr[x].second;
	      			cout<<arrPtr[x].third<<endl;
					}
         }

   }

}
	getch();
	return 0;
}

dwhitney67 · 06-23-2011, 10:49 AM

Quote:

Originally Posted by lindaonline15

can anyone tell me what is the problem with my code??

Yes... it is overkill for what you need to do.

Consider this:

Code:

#include <string>
#include <iostream>

int main()
{
   std::string input;

   std::cout << "Enter a string of numbers (eg. 12345678): ";
   std::getline(std::cin, input);

   while (!input.empty())
   {
      std::cout << input.substr(0, 3) << std::endl;

      input = input.substr((input.size() > 3 ? 3 : input.size()));
   }
}