how to initial array when reverse string

Question

the question is about leetcode 344. Reverse String

class Solution {
public:
    string reverseString(string s) {
        char *array = new char[s.length()];
        for(int i=0;i<s.length();i++)
        {    
            array[i] =s[s.length()-i-1];
        }
        string strlist(array);
        printf("%s\n",strlist.c_str());
        return strlist;
    }
};

input is "Sore was I ere I saw Eros." output is ".sorE was I ere I saw eroSnam A\""

it seems that my array has more element than I expected, and I have no idea how to avoid that, anyone can suggest that?

Why new char[]? Especially when you're already using std::string everywhere? — Quentin
– Quentin, Commented May 14, 2018 at 2:06
Why not simply -- string reverseString(string s) { std::reverse(s.begin(), s.end()); return s; }? — PaulMcKenzie
– PaulMcKenzie, Commented May 14, 2018 at 2:08
Don't mix C (e.g. char arrays, naked owning pointers, printf) and C++ (std::string, smart pointers, algorithms, iostream). — DevSolar
– DevSolar, Commented May 14, 2018 at 2:14

iBug · Accepted Answer · 2018-05-14 02:12:23Z

4

You forgot to terminate the C-style string with a null character. Also remember to delete[] the allocated array.

string reverseString(string s) {
    char *array = new char[s.length() + 1];
    //                                ^^^
    for(int i=0;i<s.length();i++)
    {    
        array[i] =s[s.length()-i-1];
    }
    array[s.length()] = 0; // Terminate the string
    string strlist(array);
    printf("%s\n",strlist.c_str());
    delete [] array; // Don't forget
    return strlist;
}

There's also some neat ways to do it:

std::string t(s);
std::reverse(t.begin(), t.end());
return t;

Or:

return std::string(s.rbegin(), s.rend());

edited May 14, 2018 at 2:12

answered May 14, 2018 at 2:05

iBug

37.6k8 gold badges101 silver badges155 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

how to initial array when reverse string

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related