Issue in reversing a string with return value?

Question

I am trying to reverse the string with return value as reversed string and input arguments as input string. Here is my code:

char* reverseString(char* string)
{
    static int i = 0;
    static char *revStr = new char[strlen(string)+1];
    if (*string)
    {
        reverseString(string + 1);
         revStr[i++] = *string;
    }
    return revStr;
}
int main(void)
{
    char* str = "Test it";
    cout << reverseString(str) << endl;;
}

output:

ti tseT═²²²²
Press any key to continue . . .

I tried this in visual studio 2013.I was expecting output to be:

ti tseT Press any key to continue . . .

But i am not getting a correct output, there are some unwanted characters getting added after "tseT". Can anyone suggest me on this? I don't want to change the function argument and return syntax.

Please explain why you are not using `std::string`? If this is an assignment with restrictions you should include them in the question so we can give appropriate answers. — Richard Critten, Aug 05 '18 at 18:45
with string class or c++11 i can easily do it, but my intention is not so. I just want to correct my function body. — A. Gupta, Aug 05 '18 at 18:47
You missed to put a raw c-string end indicator `'\0'` at the end. There are probably many more duplicates of that question. — πάντα ῥεῖ, Aug 05 '18 at 18:47
can you suggest how to modify my code to place '\0' will see if it works. — A. Gupta, Aug 05 '18 at 18:48
@A.Gupta Just put `revStr[i] = '\0';` before the `return` statement. — πάντα ῥεῖ, Aug 05 '18 at 18:50
@A.Gupta Also note that you can simply use the [`std::reverse()`](https://en.cppreference.com/w/cpp/algorithm/reverse) algorithm to achieve what you want. You don't need to use `std::string` to do that actually. — πάντα ῥεῖ, Aug 05 '18 at 18:53
Beyond failing to terminate the string properly, this has a serious problem if you call it more than once. For example, something like: `std::cout << reverseString("abc"); std::cout< — Jerry Coffin, Aug 05 '18 at 18:53
@πάντα ῥεῖ I already mentioned my intention is not to use any string class method or any normal function. Just wanted a recursive way with returning reversed string. — A. Gupta, Aug 05 '18 at 18:56
@A.Gupta That's all fine. I just wanted you make aware of that. — πάντα ῥεῖ, Aug 05 '18 at 18:57

Susmit Agrawal · Answer 1 · 2018-08-05T18:53:35.813

0

You need to take care of the final '\0'.

Try adding an else statement:

if (*string)
{
     revStr[i++] = *string;
    reverseString(string + 1);
}
else
    revStr[i] = '\0';

edited Aug 05 '18 at 18:53

answered Aug 05 '18 at 18:48

Susmit Agrawal

3,649
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I tried it but still getting the same unwanted characters at the end of "tseT" – A. Gupta Aug 05 '18 at 18:52
Make the recursive call after setting `revStr[i++]`. Check edit. – Susmit Agrawal Aug 05 '18 at 18:54
1

We do not need "else", just we need "revStr[i] = '\0';" before returning string. – A. Gupta Aug 05 '18 at 19:00

Issue in reversing a string with return value?

1 Answers1