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reversing a string

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Join Date: Sep 2008

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sunveer

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reversing a string

Oct 3rd, 2008

I want help in reversing a string without using another array.
a string "Hello" should be printed as "olleh"
Please help.

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Narue

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Re: reversing a string

Oct 3rd, 2008

Since you didn't give nearly enough information, or provide even a rudimentary attempt, this is all you get. Here's how a real-world programmer would do it:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <algorithm>
#include <string>
 
std::string s = "hello";
std::reverse ( s.begin(), s.end() );
#include <algorithm>
#include <string>

std::string s = "hello";
std::reverse ( s.begin(), s.end() );

Last edited by Narue; Oct 3rd, 2008 at 10:01 am.

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sunveer

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Re: reversing a string

Oct 3rd, 2008

i don't know algorithms and functions
Please provide the simplest code .

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Narue

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Re: reversing a string

Oct 3rd, 2008

>i don't know algorithms and functions
Yes, I figured as much.

>Please provide the simplest code .
It doesn't work that way. You prove that you've made an honest attempt, then we provide help to boost you along.

Last edited by Narue; Oct 3rd, 2008 at 10:12 am.

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Sky Diploma Sky Diploma is offline

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Re: reversing a string

Oct 3rd, 2008

>Please Provide The Simplest Code.
Well wont it be simple If You create a function to interchange the first and last char and then the last but one and second character and so on....
This should be done until They Come to the middle of the word.

Try Implementing a FLOWCHART.

1. Please Mark Your Thread as Solved After Getting Your Answers.
2. Please Use CODE TAGS .

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Salem

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Re: reversing a string

Oct 3rd, 2008

Just print it out in reverse?
Or reverse it "in place" in the string it's stored in, then print it out?

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bhoot_jb

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Re: reversing a string

Oct 3rd, 2008

i think first of all you really need to attempt it by yourself. People here will help you only if you have made some honest attempt

Bhoot

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STUDENT#101 STUDENT#101 is offline

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Re: reversing a string

Oct 6th, 2008

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Originally Posted by sunveer

I want help in reversing a string without using another array.
a string "Hello" should be printed as "olleh"
Please help.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include<iostream>
#include<string>
using namespace std;
int main()
{
string msg;
cout<<enter massage"<<endl;
cin.ignore();
getline(cin,msg);
int z=msg.length();
fo(int n=z;n>-1;n--)
{
cout<<msg[n];
}
cout<<endl;
return 0;
}
 
#include<iostream>
#include<string>
using namespace std;
int main()
{
string msg;
cout<<enter massage"<<endl;
cin.ignore();
getline(cin,msg);
int z=msg.length();
fo(int n=z;n>-1;n--)
{
cout<<msg[n];
}
cout<<endl;
return 0;
}

this is all ive got

Last edited by Narue; Oct 6th, 2008 at 9:18 am. Reason: added code tags

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Narue

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Re: reversing a string

Oct 6th, 2008

>this is all ive got
I suppose it could be worse.

>cout<<enter massage"<<endl;
You forgot the opening double quote for the string. This will cause your code to fail compilation.

>cin.ignore();
There's exactly no point to this line. In fact, it'll probably surprise users.

>int z=msg.length();
Type mismatch. length returns an unsigned quantity, the type of which can be acquired by saying string::size_type instead of int.

>fo(int n=z;n>-1;n--)
"fo", huh? I don't recall that on the list of C++ keywords. You also have an off-by-one error where you access msg[msg.length()] . Indexing in C++ is zero-based, so you're accessing the string beyond the last character.

In the interests of helping you improve, I'll teach you a trick for using unsigned types in a loop that counts down to zero. It's helpful in cases like this where you need to stop after zero, but can't actually get below zero. The trick is to rely on unsigned wraparound:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
string::size_type n = msg.length();
 
while ( --n != (string::size_type)-1 )
  cout<< msg[n];
string::size_type n = msg.length();

while ( --n != (string::size_type)-1 )
  cout<< msg[n];

When you cast -1 to an unsigned type, you get the largest value of that unsigned type. This has the same effect as decrementing an unsigned type with a value of zero.

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Reputation: STUDENT#101 is an unknown quantity at this point

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STUDENT#101 STUDENT#101 is offline

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Re: reversing a string

#10

Oct 9th, 2008

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Originally Posted by Narue

Since you didn't give nearly enough information, or provide even a rudimentary attempt, this is all you get. Here's how a real-world programmer would do it:
Help with Code Tags

C++ Syntax (Toggle Plain Text)
#include <algorithm>
#include <string>
 
std::string s = "hello";
std::reverse ( s.begin(), s.end() );
#include <algorithm> #include <string> std::string s = "hello"; std::reverse ( s.begin(), s.end() );

yes i am sorry about the qoute but as for cin.ignore() I have to disagree, I'm using linux and it is neccesary for me to include it. In a way I surpose I was wrong for forgettng the semicolon but before telling me that it the ci.ignore is not neccesary perhaps you should have asked considered the fact that we all use different compilers ohh and by the way I'm still studying programming so I go for simple sollutions that I understand sorry if I was wrong for jst trying to help thanx.