Reversing a string in c++

Question

I started doing the C++ challenges on coderbyte. The first one is:

Using the C++ language, have the function FirstReverse(str) take the str parameter being passed and return the string in reversed order.

Use the Parameter Testing feature in the box below to test your code with different arguments.

It gives u the follow starting code, which you then edit and add to to create the program:

#include <iostream>
using namespace std;

string FirstReverse(string str) { 

  // code goes here   
  return str; 

}

int main() { 

  // keep this function call here
  cout << FirstReverse(gets(stdin));
  return 0;

}

I have come up with the following:

#include <iostream>
using namespace std;

string FirstReverse(string str) {
    cout<<"Enter some text: ";
    cin>>str;
    string reverseString;

    for(long i = str.size() - 1;i >= 0; --i){
        reverseString += str[i];
    }

    return reverseString;

}

int main() {

    // keep this function call here
    cout << FirstReverse(gets(stdin))<<endl;
    return 0;

}

It gives me the following error: "No matching function to call to gets" Now, why does this happen and what can I do to fix it? Thank you for reading this and all help would be appreciated.

[Already available](http://en.cppreference.com/w/cpp/algorithm/reverse) in the standard library. An example implementation is provided too. — kebs, Feb 03 '16 at 23:05
If you used `unsigned long` you would have greater range. Never heard of a string with a negative length. — Thomas Matthews, Feb 03 '16 at 23:10
if you still want to build your own iterator_loop use reverse_iterators, see [example](http://www.cplusplus.com/reference/string/string/rbegin/) — BeschBesch, Feb 03 '16 at 23:19
@ThomasMatthews I thought if the word was backwards the length was negative? `std::string("!tahw").length() == -5` :) — Fantastic Mr Fox, Feb 03 '16 at 23:20
@Ben: str.size() as it is used in the example returns the unsigned type size_t (standard unsigned int). So it is alwaly positive — BeschBesch, Feb 03 '16 at 23:22
@user4581301 I almost believed it was possible. But i guess not. — Fantastic Mr Fox, Feb 03 '16 at 23:25
Did not react fast enough to that, it is past midnight here... Also the smiley-face is hidden behind Ben's code example :P. — BeschBesch, Feb 03 '16 at 23:26

score 3 · Accepted Answer · answered Feb 03 '16 at 23:12

3

The gets method is declared in the cstdio header.

Try #include <cstdio> or #include <stdio.h>

Edit 1: Use std::string
I recommend using std::string and std::getline.

std::string text;
std::getline(cin, text);
std::cout << FirstReverse(text) << endl;

answered Feb 03 '16 at 23:12

Thomas Matthews

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Reversing a string in c++

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