Help in string

[WongEdan]

i'm newbie in c++, and i wrote code which prompt user to input something ( in string), and i want to evaluate the input. like this

#include "iostream.h"

void main()
{
	char name[25];
		
	cout << "Enter Your Name ";
	cin >> name;
		
	if (name == 'ILO') 
                {
                     cout << "Handsome";
                }
                else
                {
                    cout << "Ugly";
                }
}

i try to compile the program , but the compiler result an error.
the message is :

"C:\BelajarCE++\LatihString\LatihString.cpp(13) : error C2446: '==' : no conversion from 'const int' to 'char *'
Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast
C:\BelajarCE++\LatihString\LatihString.cpp(13) : error C2040: '==' : 'char [25]' differs in levels of indirection from 'const int'
Error executing cl.exe."

Please help me how to handle this. thank's in advice .

[WongEdan]

Anyone ???????........

[abdul]

First, try putting the header file like this:

#include <iostream.h> 

[WongEdan]

I still got the same error.

[abdul]

What compiler are you using?

[WongEdan]

Microsoft Visual C ++

[filburt1]

Use "double quotes" for strings longer than one char, use 's'ingle quotes for one char or for escape chars like '\n'.

[abdul]

aaahhhh...did not notice that. Maybe, time to sleep

[WongEdan]

it works filburt1, but whatever i type ( include ILO) , it produce Ugly. why ?

[abdul]

How about this:

#include "iostream.h"

void main()
{
    char name[25];
        
    cout << "Enter Your Name ";
    cin >> name;
               cout<<IIF(name == "ILO","Handsome","Ugly");
return 0;        
} 

[WongEdan]

I got error C2065: 'IIF' : undeclared identifier

[transcendental]

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

void main()
{
	char name[25];
		
	cout << "Enter Your Name ";
	cin >> name;
		
	if (strcmp(name,"ILO")==0) 
                {
                     cout << "Handsome";
                }
                else
                {
                    cout << "Ugly";
                }
}

I usually do it this way. If you want to do it (if (name=="ILO"))this way , you got to use a string class, I think. I never use a string class, I am lazy, I just use the easiest knowledge available(i.e. my brain)

By the way, is your surname "Wong"?

[filburt1]

Originally posted by abdul
How about this:

#include "iostream.h"

void main()
{
    char name[25];
        
    cout << "Enter Your Name ";
    cin >> name;
               cout<<IIF(name == "ILO","Handsome","Ugly");
return 0;        
} 

Almost LOL, Iif is only in one language: VB. There's that funky inline if deal in C++ (condition ? true : false or condition : false ? true, I forget which).

[WongEdan]

Thank's transcendental.

I will try it.

that's not My surename, it just a nick name. is this have special mean for you ?

[kedaman]

Cstrings don't have an overloaded operator == to compare them.
Immediate if is equivalent with ternary operator ?:

I suggest you learn the language basics first before you continue:
Here's a good tutorial, Sam's teach yourself C++ in 21 days:
http://newdata.box.sk/bx/c/

[transcendental]

Originally posted by WongEdan
that's not My surename, it just a nick name. is this have special mean for you ?

Curious just asking.

[transcendental]

Originally posted by kedaman
Cstrings don't have an overloaded operator == to compare them.
Immediate if is equivalent with ternary operator ?:

I suggest you learn the language basics first before you continue:
Here's a good tutorial, Sam's teach yourself C++ in 21 days:
http://newdata.box.sk/bx/c/

Hi, kedaman, does the ANSI C++ have a string class? Curious. When I say string class, I am not refering to MFC's CString class.

Practical C++ book uses it all the time. small capital s in string class. #include<string>

[kedaman]

yeah, there's a class template basic_string which string is instantiated from, i've never used it though, Cstrings have been good enough for me since i don't do anything advanced with them.

[abdul]

Originally posted by filburt1


Almost LOL, Iif is only in one language: VB. There's that funky inline if deal in C++ (condition ? true : false or condition : false ? true, I forget which).

Totally totally messed up...damn I have seen this "ratio" if in javascript too but I was thinking of vb one

[transcendental]

This code below compiles and works with Dev-C++ and Free Borland compiler.

#include<string>
#include<iostream>

using namespace std;

int main(void)
{
      string holder;
      holder="myname";
      if (holder=="myname")
          cout<<"Yes"<<endl;
      else
          cout<<"No"<<endl;
      return 0;
}

This is working VC code below.

CTest_CStringDlg::OnOK() 
{
	// TODO: Add extra validation here
	CString holder;
	holder="myname";
	if (holder=="myname")
    	MessageBox("Yes");
	else
		MessageBox("No");
	CDialog::OnOK();
}

[CornedBee]

Oh my god............................................
Immediate if is
condition ? true : false;
C-Strings don't have a == operator. To use == you must either use string from the header <string> or the MFC CString (what you do ONLY in MFC apps). To compare C-strings, always use strcmp. It returns 0 if the strings are equal. It is declared in <strings.h> or (real C++) <cstring>. If you use the == operator with C-strings you compare the MEMORY ADDRESSES!
the string class is ANSI C++.
Use
#include <iostream>
using namespace std;

this is ANSI C++, iostream.h may disappear someday.
the <string> header also contains a class named wstring for UNICODE strings.

trans: the reason why the codes works is because the == operator is overloaded in CString and string.
But even this code would work:

char* str = "Hello":
if(str == "Hello") // ...

I'm not 100% sure, but I think this would work, because:
In every exe, the hardcoded strings are stored at a specific region. Every string is stored only once, if you use exactly the same string twice, both will refer to the same location.
If you write:
char* str = "Hello";
the address of the string "Hello" in the exe is assigned to str. Now you can work with the string.
If you later write:
if(str == "Hello")
you compare the memory adderss in str and the address of the string "Hello". Those are the same, so the statement returns true. I'm not sure, but I think this code will still enter the if:

char* str = "Hello";
str[2] = t;  // string is now "Hetlo"
if(str == "Hello")
{ // I think execution will get here...
}

keda or parksie, do you think this works? I'm too lazy to try...

[kedaman]

You're right, a string is char* and pointer aritmethic applies on all pointers, except for str[2] = t; the code compiles

[CornedBee]

does it only compile or does the if fire too?

[kedaman]

It fires, and i guess the optimizer placed both reference to "Hello"at the same place

[CornedBee]

I think every compiler does it, not only when optimized, but also when in debug mode.

[CornedBee]

OK it should be
str[2] = 't';
and this produces an access violation because I'm trying to change the exe, which is write-protected.
But if I remove that, it even works in debug mode.

[kedaman]

It's in the exe of course, since it's a constant, otherways it wouldn't have optimized it to use the same string.
I got an access violation

[CornedBee]

me too.