Make a backward string its own string? - c++

Question

I am brand new to programming so none of this may be right. I was just messing around trying to get the effect that I (finally) achieved. More for practice than anything else, but I wondered if there was another way to do it.
#include "stdafx.h"
#include <conio.h>
#include <iostream>
#include <string>
using namespace std;
int main()
{
string str1="Don't even think about it!";
string str2;
string str3;
string str4 = "";
for (int i = 0; i < str1.length(); i++){
str2 = str1.substr (0, str1.length()-i);
cout << str2 << str4;
for (int x = str2.length() - 1; x >= 0; x--){
str3 = str1[x];
cout << str3;
}
str4 = str4 + " ";
cout << "\n";
}
getch();
main();
return 0;
}
The question I have is this: Is there a way to make the str3, after it is backwards, its own string that I could then justify right instead of adding spaces with str4?

Answer 1

In order to get a reversed string, just pass the reverse-iterators to the constructor of a new string:
#include <iostream>
#include <string>
int main() {
std::string s = "this is a test";
std::string s_reversed(s.rbegin(), s.rend());
std::cout << s << "\n" << s_reversed << "\n";
}
The output is:
$ g++ test.cc && ./a.out
this is a test
tset a si siht
Applied to your problem:
#include <iostream>
#include <string>
int main() {
std::string s = "this is a test";
for (auto i = s.length(); i > 0; i--) {
std::cout << s;
std::cout << std::string(s.rbegin(), s.rend());
std::cout << '\n';
s[i-1] = ' ';
}
}
Note that there also is an algorithm in the standard library to reverse a container, e.g., a string: std::reverse().
For reference:
http://en.cppreference.com/w/cpp/string/basic_string/basic_string
http://en.cppreference.com/w/cpp/string/basic_string/rbegin
http://en.cppreference.com/w/cpp/string/basic_string/rend
http://en.cppreference.com/w/cpp/algorithm/reverse

Answer 2

You could try this:
replacing letters for whitespace and then reversing the string.
Concat the modified string with the reverse of it and print it.
std::string reverse(std::string str)
{
std::reverse(str.begin(), str.end());
return str;
}
int main()
{
std::string str = "Don't even think about it!";
size_t N = str.length();
for (size_t i = 1; i < N; i++)
{
std::cout << str << reverse(str) << std::endl;
str.replace(N-i,1, " ");
}
return 0;
}

Answer 3

First I would rename the variables so it is more clear what you are trying to achieve. Believe me, in two months you will not have a clue what this code actually does. Suggestion:
str1 -> baseString
str2 -> forwardsClippedString
str3 -> backwardsClippedString
str4 -> gapString
Maybe these names are not even good but I think they are better than str1, ..., str4.
Then I would make a separate method of the inner loop. After that make a separate method of the outer for loop - yes, main() shouldn't be complicated at all.
Finally instead of recursively calling main I suggest to do a while-loop. An infinite one if you please (but it would be nice if one key quits the loop then).