need a little C++ help

[cocacola]

i need to write a function that will display all possible strings of lowercase letters, for instance..

a
b
c
d
...
x
y
z
aa
ab
ac
ad
...


and so forth (up to say, 5 characters). i'd really appreciate source code, but if someone can just point me in the right direction, i would be greatful.

i know it can be done with loops, but i'd prefer a way which is a little more tactful.

can this be done with recursion?

anyway, i appreciate any help i can get.

[RiOtEr]

umm if you cant figure out this with loops your not going to be able to do recursion lol
its pretty hard calling functions within functions
i have a source somewhere to do this if i cant find it ill write one up
pm if you have any major questions
RiOtEr

[Kezil]

for now, here's one with loops (and yes, I know this isn't what you asked for, or to clean, but it may start you off):

#include <stdio.h>

void PrintList();

int main()
{
	int choice;
	puts( "press 1 to run, 2 to exit" );
	scanf("%d", &choice );
	
	if ( choice = 1 )
		PrintList();

	return 0;
}
   	
void PrintList()
{	
   int c1, c2, c3, c4, c5; 
   char ch1, ch2, ch3, ch4, ch5;
   char alpha[28] = " abcdefghijklmnopqrstuvwxyz";
   
   c1=0;
   c2=0;
   c3=0;
   c4=0;
   c5=1;
   while ( c1 < 27 )
   {
	   while ( c2 < 27 )
	   {
		   while ( c3 < 27 )
		   {
			   while ( c4 < 27 )
			   {
				   while ( c5 < 27 )
				   {
					   
					   ch1 = alpha[c1];
					   ch2 = alpha[c2];
					   ch3 = alpha[c3];
					   ch4 = alpha[c4];
					   ch5 = alpha[c5];
					   
					   printf( "%c%c%c%c%c", ch1, ch2, ch3, ch4, ch5 );

					   c5++;				   
				   }
                   c4++;
				   c5=1;
			   }
			   c3++;
			   c4=1;
		   }
		   c2++;
		   c3=1;
	   }
	   c1++;
	   c2=1;
   }
}

[smirc]

Ok here's something that I kludged together. Using recursion for this is a BAD idea. You'll run out of stack space really fast for a brute force algorithm like this. You can implement anything that uses recursion using iterative structures instead so that's what I recommend. The following code will do what you want. I used Borland C++ 5.0 since you didn't specify a compiler.

#include <iostream>
#include <string>
using namespace std;

string num2base(int, int, int);

int main() {

    // change these to use a different range of ascii chars
    char LOWER_BOUND = 'a';
    char UPPER_BOUND = 'z';

    // change this to vary the string length
    int STRING_LENGTH = 5;

    int TOTAL_PERMUTATIONS = pow((UPPER_BOUND - LOWER_BOUND + 1), STRING_LENGTH);
    string s;

    for (int i = 0; i < TOTAL_PERMUTATIONS; i++) {
        s = num2base(i, (UPPER_BOUND - LOWER_BOUND + 1), LOWER_BOUND);
        if (s == "") {
            cout << (char)LOWER_BOUND << endl;
        } else {
            cout << s << endl;
        }
    }
}

string num2base(int num, int base, int offset) {

    string s = "";
    while(num) {
        s = s + (char)((num % base) + offset);
        num = (num / base);
    }
    return s;
}

Hope this helps .

[cocacola]

THANKS SMIRC!!!

that's perfect!
exactly what i was looking for.

btw, if anyone wants to use smirc's code, you might have to add:

#include <math.h>

for the power function. (i had to with visual c++)

[smirc]

No problem, glad I could help. Borland does most includes automatically so I didn't have to explicitly include the math.h library. I probably should have done this but (like I said) this was a very quick and dirty solution but it does the job .