Reversing a string using stack

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Hi,
I am a beginner in C++ and I was trying a program in C++ to reverse a string using C++ but its giving all sorts of problems. I don't intend to initialize the string in the code itself.

C

#include <iostream>
#include <string>
#include <stack>
#include <cstring>

using namespace std;

int main()
{
    int i=0;
    string text;
    stack<char> s;
    cout<<"Enter a string: ";
    cin>>text;
    for(int i=0;i<text.length();i++)
    {
    //text.length takes only one word and doesn't count whitespaces.
        s.push(text[i]);
    }
    while(!s.empty())
    {
        cout<<s.top();
        s.pop();
    }

I tried converting this string into text.c_str() and then pushing each of them in the stack but I was erring somewhere in the syntax since I new in this. What would be the correct way to do this?

Posted 23-Dec-10 1:11am

optimus_prime1

Updated 23-Dec-10 2:39am

Tony Richards

v2

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Tony Richards 23-Dec-10 8:40am

Cleaned up the code a little, fixing problems with angle brackets being mistaken for HTML tags.

Dr.Walt Fair, PE 23-Dec-10 10:11am

I think you asked this twice. Don't do that!

3 solutions

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Manfred Rudolf Bihy · Answer 1 · 2010-12-23T03:00:00

Solution 1

Wouldn't you have to create a stack<char> instance first? I'm not even ankle deep into C++, so I'm taking a guess here: stack<char> s = new stack<char>();
or something like that. Look it up.
Please answer my question also, why do you keep posting questions with no inidication of what error actually occurred. That is the least you could do as it would make it easier for us to help you.

Cheers,

Manfred

Posted 23-Dec-10 3:00am

Manfred Rudolf Bihy

Updated 23-Dec-10 3:01am

v2

Comments

optimus_prime1 23-Dec-10 9:06am

I actually wrote the problem in the code comment. Sorry about this :|

Manfred Rudolf Bihy 23-Dec-10 9:17am

Well, what you wrote in your code is not correct. Read here:
http://msdn.microsoft.com/en-us/library/system.string.length.aspx
I do recommend you buy yourself a book on C++ programming.

optimus_prime1 23-Dec-10 10:38am

Ya! trying programs from the book but sometimes mess up... :-/

optimus_prime1 23-Dec-10 10:41am

You mean text.length() is not correct? or text.length() does count length of the string including spaces?
(btw, I am trying Win32 console and not MFC)

Manfred Rudolf Bihy 23-Dec-10 13:03pm

I meant to say that text.length() counts the length of the whole string.

Dalek Dave 23-Dec-10 20:19pm

Good Answer.

optimus_prime1 24-Dec-10 0:16am

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

int main()
{
string text;
cin>>text;
cout<<text.length();
return 0;
}

Input: How are you?
Output: 3
Screenshot: http://img802.imageshack.us/img802/8473/scr.png
I don't think text.length() is counting the whole string when I giving a string at the runtime...
However, if I write string text = "How are you?", then it will give the answer as 12.

T2102 · Answer 2 · 2010-12-23T12:46:00

Solution 2

I'm not sure why you are using a stack to print out the reversed the string. Why not just iterate backwards?

for (int i=text.length()-1; i>=0; i--)

Posted 23-Dec-10 12:46pm

T2102

ShilpiP · Answer 3 · 2010-12-23T18:43:00

Solution 3

In your program cin only take one word for example if i type "my name is xyz" than the string only get "my".

getline(cin,text,'\n')

may solve your problem.

Posted 23-Dec-10 18:43pm

ShilpiP

Comments

optimus_prime1 24-Dec-10 1:15am

That actually did solve but what I earlier used getline was like this: cin.getline(ch,256);
How should I have known to use getline(cin,text, '\n')? :-/

ShilpiP 24-Dec-10 1:54am

cin.getline(ch,256); is ok if you are using char pointer and if you are using std::string than it is better you use std::getline.

optimus_prime1 24-Dec-10 2:09am

So, for char and string getline has different syntax?
For char- cin.getline(ch,256);
For string- getline(cin,text,'\n');
Is it?
Then what's the difference between cin.get(text,'\n'); and cin.getline(ch, 256); ?

ShilpiP 24-Dec-10 4:11am

cin is istream object

basic_istream Members are get and getline
get: Reads one or more characters from the input stream.
getline: Reads a line from the input stream.

you are using basic_string in your code it has the api with name getline
this api is declared in
#include<string>
using namespace std;
:)

Now please search on net and find out the difference of get and getline.
getline in istream and getline in basic_string. :)