Reverse String

[Vlatko]

_strrev, _wcsrev, _mbsrev
Reverse characters of a string.

char *_strrev( char *string );

wchar_t *_wcsrev( wchar_t *string );

unsigned char *_mbsrev( unsigned char *string );

Routine Required Header Compatibility 
_strrev <string.h> Win 95, Win NT 
_wcsrev <string.h> or <wchar.h> Win 95, Win NT 
_mbsrev <mbstring.h> Win 95, Win NT 


For additional compatibility information, see Compatibility in the Introduction.

Libraries

LIBC.LIB Single thread static library, retail version 
LIBCMT.LIB Multithread static library, retail version 
MSVCRT.LIB Import library for MSVCRT.DLL, retail version 


Return Value

Each of these functions returns a pointer to the altered string. No return value is reserved to indicate an error.

Parameter

string

Null-terminated string to reverse

Remarks

The _strrev function reverses the order of the characters in string. The terminating null character remains in place. _wcsrev and _mbsrev are wide-character and multibyte-character versions of _strrev. The arguments and return value of _wcsrev are wide-character strings; those of _mbsrev are multibyte-character strings. For _mbsrev, the order of bytes in each multibyte character in string is not changed. These three functions behave identically otherwise. 

Generic-Text Routine Mappings

TCHAR.H Routine  _UNICODE & _MBCS Not Defined _MBCS Defined _UNICODE Defined 
_tcsrev _strrev  _mbsrev  _wcsrev  


Example

/* STRREV.C: This program checks an input string to
 * see whether it is a palindrome: that is, whether
 * it reads the same forward and backward.
 */

#include <string.h>
#include <stdio.h>

void main( void )
{
   char string[100];
   int result;

   printf( "Input a string and I will tell you if it is a palindrome:\n" );
   gets( string );

   /* Reverse string and compare (ignore case): */
   result = _stricmp( string, _strrev( _strdup( string ) ) );
   if( result == 0 )
      printf( "The string \"%s\" is a palindrome\n\n", string );
   else
      printf( "The string \"%s\" is not a palindrome\n\n", string );
}


Output

Input a string and I will tell you if it is a palindrome:
Able was I ere I saw Elba
The string "Able was I ere I saw Elba" is a palindrome

[MidgetsBro]

That is some very nice code, but can I print the string reversed to the screen? And can I use cin and cout? I am doing this for class, and we haven't learned how to use the printf statement.

[kourosh]

Well talking about the strings, I have came across a problem.

I am reading a book on C++ and one of the programs is

#include<iostream.h>
#include<string.h>

int main()
{
String Name;
cout<< "Enter your Name: ";
cin>> Name;
and so on...
return 0;
}

and when I compile the program, the compiler doesn't recognize the String and tells me it is undeclared identifier. Anybody haves any idea why this happens?

[HarryW]

Are you sure it's "String" and not "string" ?

[kourosh]

Originally posted by HarryW
Are you sure it's "String" and not "string" ?

Hi, Yeah I am pretty sure it is String. Although instead of string.h I have tried other libraries but i get the same errors. I tried:
string.h
String.h
wchar.h
mbstring.h

But non of them works. I have absoloutly no clue why this happen.

P.S. I know I have all the libraries in my include folder.

Any guesses??

Thanks in advance

[HarryW]

Okay, try

#include <string>

without the .h at the end. <string> is the STL string library (the ANSI standard), <string.h> is Microsoft's version. In <string> there should be a class called 'string'. I think it's all lower case, but I'm not certain.

[parksie]

string.h
A set of functions for manipulating chararacter arrays.

string
Part of the STL -- includes the string class.

To use string:

#include <iostream> // You must use this version!
#include <string>

void main() {
    string x;
    cin >> x;

    cout << x << endl;
} 

You seem to have left out something important.....

#include <iostream> // You must use this version!
#include <string>
using namespace std; //this is needed!
void main() {
    string x;
    cin >> x;

    cout << x << endl;
} 

[parksie]

Oops....yep. I did miss it - thanks Dennis

I suppose this is what happens when you're at 39 degrees ....damn I'm not thinking straight

[HarryW]

Why must he use the ANSI version? Why is it so essential?

is it because <string> won't work with <iostream.h> ?

[Vlatko]

This post was simply on how to reverse a string

#include <iostream.h>
#include <windows.h>

int main() 
{ 	
char str[] = "Vlatko";
cout<<strrev(str)<<endl; 
return 0; 
}

[parksie]

Yes.

Well...it will work with it, but you can't do cin >> string with it.

[MidgetsBro]

Thank you Vlatko! That was all I needed.

[kourosh]

Originally posted by denniswrenn

using namespace std; //this is needed! 

Thanks alot to everybody, although I had one more question what does
using namespace std; do??


Thanks again.

it "uses" the std namespace...

ex:

#include <iostream>

int main()
{
std::cout << "test";
return 0;
} 

if theres only a few cout's, that isn't so bad is it?

but if theres about 50... well, look how messy this is...

#include <iostream>
#include <string>

int main()
{
    std::string str
    std::cout << "enter a string" << std::endl;
    std::cin >> str;
    std::cout << str << " is the value of str" << std::endl;
    return 0;
} 

if you use using namespace std you don't need to use std::