string decoder

[award982]

hey all!

I am writing a program that takes a string, and tries to create the copy of it using all possible combinations, like a sort of bruteforce.
Can someone help me? this is what i have:

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

int main(int argc, char *argv[])
{
   string a; 
   getline(cin,a);
   char b[a.length()];
   for(int l = 0;l<a.length();l++){
           b[l]='a';
           }
   int num = 0;
    for(int i = 0;i<a.length();i++){
            for(int z = b[i];z<300;z++){
                    b[i]=z;
                    
                    cout<<b<<endl;
                    
                    }
            if(a==b){
                     cout<<"works";

                     }
            }
    
    
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

This doesnt work. I am trying to decode using the ansi table, witch every character of the array b starts at a, and add to it until it is 300.
Can someone point out what i am doing wrong?
Thanks in advance!

[Scott Vass]

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

int main(int argc, char *argv[])
{
	string a = "Hi!";	// Can't be bothered with input from user.
	bool found = false;
	int num = myString.length()+1; // An extra char for NULL-terminating.
	char * b = new char[num];
	for(int x = 0; x < num; ++x)
		copy[x] = 0;	// Init to zero.
	for(int i = 0; (i <= 300) && !found; ++i) {	// Three letters. Three levels of loops.
		for(int j = 0; (j <= 300) && !found; ++j) {
			for(int k = 0; (k <= 300) && !found; ++k) {
				copy[0] = i;
				copy[1] = j;
				copy[2] = k;
				if(strcmp(copy, myString.c_str()) == 0)
					// Match found.
					found = true;
			}
		}
	}
	if(found)
		cout << "String is: " << b << endl;
	else
		cout << "Couldn't copy string." << endl;
	system("PAUSE");
	return EXIT_SUCCESS;
}

[Scott Vass]

Doh! I like to use different variable names to you.
With this algorithm, anything more than 4 or 5 letters becomes a little too long to wait for. Reducing the scope of ASCII table values to check helped a little, but nothing to brag about.
I don't know how you'd modify this code to work for any given length string.

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

int main(int argc, char *argv[])
{
	string a = "Hi!";	// Can't be bothered with input from user.
	bool found = false;
	int num = a.length()+1; // An extra char for NULL-terminating.
	char * b= new char[num];
	for(int x = 0; x < num; ++x)
		b[x] = 0;	// Init to zero.
	for(int i = 32; (i <= 126) && !found; ++i) {	// Three letters. Three levels of loops.
		for(int j = 32; (j <= 126) && !found; ++j) {
			for(int k = 32; (k <= 126) && !found; ++k) {
				b[0] = i; 
				b[1] = j; 
				b[2] = k;
				if(strcmp(b, a.c_str()) == 0)
					// Match found.
					found = true;
			}
		}
	}
	if(found)
		cout << "String is: " << b << endl;
	else
		cout << "Couldn't copy string." << endl;
	system("PAUSE");
	return EXIT_SUCCESS;
}