Problem in printing characters by using class

[Basit781]

Hi to all,
Hope you all will be fine. I am new to C++. Although i have read the basics but i am a newbie to C++.
Now i want to learn how to use class in C++. For this i made a simple class, assign variables and simply try to assign values to variables. But i got errors

I wrote very simple code

class Test {
public:
    Test(char* firstNamePointer, char lastName[]);
    Test(const Test& orig);
    virtual ~Test();

    int item;
    char *firstNamePointer;
    char lastName[10];
   
   // string middleName;

private:

};

Test::Test(char* firstNamePointer, char lastName[]) {

    this->firstNamePointer = firstNamePointer;
    this->lastName = "Mahmood";
    //this->lastName = lastName;
}

Test::Test(const Test& orig) {
}

Test::~Test() {
}

int main(int argc, char** argv) {

    Test *test = new Test("Basit", "Mahmood");
    test->item = 5;
   
    //test->middleName = "Ahmed"

    cout << (*test).item << endl;      //ok
    cout << test->item << endl;        //ok

    cout << endl;
    cout << (*test).firstNamePointer << endl;      //ok
    cout << test->firstNamePointer << endl;        //ok

    cout << endl;
    cout << (*test).lastName << endl;
    cout << test->lastName << endl;

    return (EXIT_SUCCESS);
}

Error that i got in the case

Test::Test(char* firstNamePointer, char lastName[]) {

    this->firstNamePointer = firstNamePointer;
    this->lastName = "Mahmood";                        //error
}

is

Test.cpp:13: error: incompatible types in assignment of `const char[8]' to `char[10]'

and when i use this code

Test::Test(char* firstNamePointer, char lastName[]) {

    this->firstNamePointer = firstNamePointer;
    this->lastName = lastName;                             //error
}

then the error is

Test.cpp:14: error: incompatible types in assignment of `char*' to `char[10]'

Also when i try to use string in my code like this

#include <string.h>  //also try <string> and <strings.h>

class Test {
public:
    Test(char* firstNamePointer, char lastName[]);
    Test(const Test& orig);
    virtual ~Test();

    int item;
    char *firstNamePointer;
    char lastName[10];
   // char lastName[10] = "Ahmed";
    string middleName;                        //Unable to resolve identifier string

private:

};

why it saying unresolved identifier string even i am including file <string.h>.
How can i use string in my class.

Please tell what i am doing wrong

thanks

[laserlight]

The problem is that you cannot assign to an array. You are heading towards a correct solution, i.e., to use std::string, but you need to #include <string> and qualify string as std::string.

[TheRogue]

I would suggest you go with the string for all "strings".

use #include <string> //string.h isn't a C++ header.

then use std::string (string is part of the std namespace)

std::string middleName ;

[Basit781]

Hmm, thanks. The string problem is solved now. But i want to ask something

I think in the code

Test::Test(char* firstNamePointer, char lastName[], string middleName) {

    this->firstNamePointer = firstNamePointer;
   // this->lastName = "Mahmood";
   // this->lastName = lastName;                  //name = testArray; 
    this->middleName = middleName;
}

I am trying to do something like this

int main(int argc, char** argv) {
    
    char name[10];
  
    char testArray[20] = "Masood";

    name = testArray;    // this is what i am actually doing in my class( // this->lastName = lastName;)   error
    
    cout << name << endl;

     //char lastName[10] = "Masood";

    // cout << lastName << endl;
}

Is it?

But when i change line like this

name[0] = testArray[0];

then i got output like this

M[]"a/    //[] is not actually brackets it's something unknown

I want to ask the output should be simple "M". what is this ([]"a/)

second i want to ask why this statement is not working. I simply trying to assign value to public member field

  test->item = 5;                     //ok
 
  test->lastName = "Masood";    //error why

i think this is same as

char lastName[10] = "Masood";

is test->lastName = "Masood"; can be interpreted something like this when i declared lastName variable in a class?

char * const lastName[10]

that's why i am getting error like this

main.cpp:24: error: incompatible types in assignment of `const char[7]' to `char[10]'

Thanks

[Basit781]

this is working

[code]
test->lastName[0] = 'M';
test->lastName[1] = 'a';
test->lastName[2] = 's';
test->lastName[3] = 'o';
/[code]

[laserlight]

I already told you that you cannot assign to an array

[Basit781]

Hmm now i understood . Actually i was confused about the working of code. I was mixing these code

   char lastName[] = {'M', 'a', 's', 'o', 'o', 'd'};  //same as  char firstName[] = "Masood";

   char firstName[] = "Masood";

   char middleName[10];

   middleName = "Masood";   // main.cpp:38: error: incompatible types in assignment of `const char[7]' to `char[10]'

And after understanding this, i came up with this and it's working very well.

#ifndef _TEST_H
#define	_TEST_H

#include <string>

using namespace std;

class Test {
public:
    Test(char* firstNamePointer, char lastName[], string middleName);
    Test(const Test& orig);
    virtual ~Test();

    int item;
    char *firstNamePointer;
    char lastName[10] ;
    string middleName;

private:

};

#endif	/* _TEST_H */

#include "Test.h"

Test::Test(char* firstNamePointer, char lastName[], string middleName) {

    this->firstNamePointer = firstNamePointer;
    strcpy(this->lastName, lastName);
    this->middleName = middleName;
}

Test::Test(const Test& orig) {
}

Test::~Test() {
}

#include <stdlib.h>
#include <iostream>

#include "Test.h"

int main(int argc, char** argv) {

    Test *test = new Test("Basit", "Ahmed", "Mahmood");

    test->item = 5;                     //ok
    //test->middleName = "Kashif";      //ok
   // strcpy(test->lastName, "Masood"); //ok

   // test->lastName[0]= 'M';           //ok
   // test->lastName[1]= 'a';           //ok

    cout << (*test).item << endl;
    cout << test->item << endl;
    cout << endl;

    cout << (*test).firstNamePointer << endl;
    cout << test->firstNamePointer << endl;
    cout << endl;

    cout << (*test).middleName << endl;
    cout << test->middleName << endl;
    cout << endl;

    cout << (*test).lastName << endl;
    cout << test->lastName << endl;
    cout << endl;

    return (EXIT_SUCCESS);
}

Thanks

[Paul McKenzie]

Hmm now i understood . Actually i was confused about the working of code. I was mixing these code

Why are you using char* for string data at all?

Your program is easily broken if I give it a last name that is more than 10 characters.

    int item;
    char *firstNamePointer;
    char lastName[10] ;
    string middleName;

Get rid of the char* and use std::string for all string data.

Test test("Basit", "ThisisaLongLastName", "Mahmood");

This will fail with your code.

Secondly:

 Test *test = new Test("Basit", "Ahmed", "Mahmood");

    test->item = 5;                     //ok

Why are you using "new" here? This is an indication you don't know how to properly instantiate objects, and not just an oversight.

Test test("Basit", "Ahmed", "Mahmood");

Then you don't need "new".

And after understanding this, i came up with this and it's working very well.

It doesn't work. I showed you how it is easily broken with a last name of more than 10 characters.

When you write a C++ application, you attempt to make it as bug-free as possible. To do this, you use the safest constructs, one being the use of string classes, not 'C' char* handling as you've done.

Regards,

Paul McKenzie

[monarch_dodra]

   char lastName[] = {'M', 'a', 's', 'o', 'o', 'd'};  //same as  char firstName[] = "Masood";

Wrong.

   char lastName[] = {'M', 'a', 's', 'o', 'o', 'd', '\0'};  //same as  char firstName[] = "Masood";

"" is automatically null-terminated. Not the case with arrays. Don't forget to null terminate your character strings.

[Basit781]

Hi
Mr. Paul i read your comments and i am very thankful to you for giving me suggestions. I greatly appreciate your suggestions. But as i already told that i am newbie so it was just an exercise.

Why are you using char* for string data at all?

Your program is easily broken if I give it a last name that is more than 10 characters.

I know it, but i want to see how you can assign value to character array when you use class. I also used string when i was trying this code, you can see in my first post

Why are you using "new" here? This is an indication you don't know how to properly instantiate objects, and not just an oversight.

Actually when i first tried this code then i didn't use new, instead i used the syntax, you suggested

Test test("Basit", "Ahmed", "Mahmood");

test.item = 5;
strcpy(test.lastName, "Masood);
....

But i am reading a book in which i encountered advance Pointers topic. In this topic the author used linked list and Tree structures. Although i didn't read the whole topic but i saw the new syntax.
So i tried it with new syntax just like that. I want to see how you can access variables when you used simple construction and when you use new (difference between . and ->) . You can see i used two syntax for printing data

    cout << (*test).firstNamePointer << endl;
    cout << test->firstNamePointer << endl;
    cout << endl;

i used it for my understanding.The whole thing was just an exercise. And once you tole me that whenever you have some problem just write simple code and then ask
But thank you very much for giving me good C++ programming suggestions

Thanks monarch_dodra for correcting me about character array null terminator

Thanks