I am new to c++ & don't know the basics all that well. pls help (sorry if the solution to this is already available, but I couldn't find any)
This is the Error I am getting:
expected primary-expression before ‘]’ token
char CusName[50]=x[];
^
For this code below:
#include <iostream>
using namespace std;
class BankAccount
{
private:
char CusName[50];
char CusId[10];
float accBalance, dep, witd;
public:
void setCusDetails(char x[], char n)
{
char CusName[50]=x[];
}
};
int main()
{
BankAccount customer1;
char cus1Name[50];
cin>>cus1Name;
customer1.setCusDetails(cus1Name, 50);
return 0;
}
Your char array looks like a string. Try using std::string instead and prefer using const references for function parameters.
If you want to use char arrays, and if your point was to copy a null-terminated string by value, then use functions like strncpy.
Using std::string may be easier for you to hide the burden of memory allocation and discover the language step by step.
You can instead use string to input and pass values.
#include <iostream>
using namespace std;
class BankAccount
{
private:
string CusName; //CusName of type string
char CusId[10];
float accBalance, dep, witd;
public:
void setCusDetails(string str, char n) //parameter str of type string
{
CusName=str; //Assign it to the already declared 'CusName' variable.
}
};
int main()
{
BankAccount customer1;
string cus1Name;
cin>>cus1Name;
customer1.setCusDetails(cus1Name, 50);
return 0;
}
Related
I have a class BankAccount with two string members - name and num. What I want is to assign values to these objects when I create them (when the constructor is called). However the compiler says No instance of constructor matches the argument list when I try to create an object.
I would like to ask why is that?
// hwk-2.cpp : This file contains the 'main' function. Program execution begins and ends there.
//
#include "pch.h"
#include <iostream>
#include <string>
#include <stdio.h>
using namespace std;
class BankAccout {
char name[23];
char num[15];
double sum;
public:
BankAccout(char *nm, char *nr, double s) {
strcpy(name,nm);
strcpy(num, nr);
sum = s;
}
};
int main()
{
BankAccout k("Peter", "0403940940", 34.21);
}
as a coffee break exercise here is more idiomatic version
#include "pch.h"
#include <iostream>
#include <string>
class BankAccount {
std::string name_;
std::string num_;
double sum_;
public:
BankAccount(std::string name, std::string num, double sum) {
name_ = name;
num_ = num;
sum_ = sum;
}
};
int main()
{
BankAccount k("Peter", "0403940940", 34.21);
}
The signature of the constructor does not match.
This one will match:
BankAccount(const char *nm, const char *nr, double s);
EDIT:
The reason is the way you are calling the constructor in the main function. You are giving literal strings as parameters. These literals are const, you cannot change them at runtime. Thus you will pass pointers to const char*.
This is very obvious if you look at this opposing example. This is a way that would be compatible with the old signature BankAccout(char *nm, char *nr, double s);.
int main(int argc, char* argv[])
{
char name[] = "hello";
char number[] = "1234";
std::cout << "name before: " << name << std::endl;
BankAccount k(name, number, 8.5);
// name and number are not const,
// you can change them :
name[2] = 'x';
name[3] = 'x';
std::cout << "name after: " << name << std::endl;
return 0;
}
An even simpler version, if you don’t need to have additional functionality in the class: just use a struct.
#include <string>
struct BankAccount {
std::string name;
std::string number;
double balance;
};
int main() {
BankAccount account{"Joy", "44", 43.};
}
**On my main i can't add a note on my new Object of the Class Trabalho
ass.add_nota(num);
**
There is a error on my compilation.
My "Trabalho.h" code:
#include <string>
#include <vector>
#include <iostream>
//#include "Enunciado.h"
//#include "Pessoa.h"
using namespace std;
class Estudante;
class Enunciado;
template <class T>
class Trabalho{
static int id_auxiliar;
string texto;
int ano;
int id;
vector<float> calif;
T* Enun;
vector<Estudante*> estudantes;
vector<Enunciado*> enunciados;
public:
Trabalho();
Trabalho(string texto, vector<Estudante*> est, T* en, int ano);
~Trabalho();
void set_texto(string texto);
string get_texto();
void add_nota(float nota);
void add_enun(Enunciado* en){Enun = en;};
int get_id(){return id;};
int get_ano() {return ano;};
void reutilizar(int id_enun);
vector<float> get_calif() {return calif;};
vector<Estudante*> get_estudantes() {return estudantes;};
Enunciado* get_enunciado() {return Enun;};
};
#endif
And my main code:
int main(int argc, char const *argv[]) {
int n;
int m;
Pesquisa ah();
float num = 1.1;
Trabalho<Pesquisa> ass();
Trabalho<Pesquisa>* tass = new Trabalho<Pesquisa>();
ass.add_nota(num);
tass->add_nota(num);
#ifndef ENUNCIADO_H_
#define ENUNCIADO_H_
#include "trabalho.h"
#include "Pessoa.h"
#include <string>
using namespace std;
class Enunciado
{
static unsigned int id_auxiliar;
const unsigned int id;
string titulo;
string descricao;
vector<int> anos_utilizados;
static unsigned int max_util;
public:
Enunciado(string titulo, string descricao);
virtual ~Enunciado();
int get_id(){return id;};
void set_titulo(string titulo);
string get_titulo();
void set_descricao(string descricao);
string get_descricao();
vector<int> get_anos_utilizados();
void mod_max_util(int a);
};
class Pesquisa: public Enunciado{
vector<string> ref;
public:
Pesquisa(string tit, string des, vector<string> refe);
};
class Analise: public Enunciado{
vector<string> repositorios;
public:
Analise(string tit, string des, vector<string> repos);
};
class Desenvolvimento: public Enunciado{
public:
Desenvolvimento(string tit, string des);
};
#endif
Both ways when i create a new Trabalho when i define my type (pesquisa is a class type on #include "Enunciado.h".
This is the two erros that appears:
"Description Resource Path Location Type
request for member 'add_nota' in 'ass', which is of non-class type 'Trabalho()' Test.cpp /Trabalho1/src line 42 C/C++ Problem
"
And:
Description Resource Path Location Type
Method 'add_nota' could not be resolved Test.cpp /Trabalho1/src line 42 Semantic Error
Can anyone help?
Thank you !
Your error is in trying to call the default constructor as
Pesquisa ah();
or
Trabalho<Pesquisa> ass();
Unfortunately, C++ is very misleading in this and it would declare your variable ass of type Trabalho<Pesquisa>(), which means "a function of zero arguments returning Trabalho<Pesquisa>" and that's exactly that the compiler error says: a function type is not a class type and as such does not have the member add_nota. Indeed, it does look exactly like a function declaration, if you look at it that way:
int main();
^ ^ ^
type arguments
name
It's a very common mistake, especially for those coming from a Java background. But it can easily catch a C++ programmer off guard as well. More information can be found here or here or here, you can see that the same error message has perplexed a good many people.
If you have a compiler conforming to the C++11 language revision, try replacing all those occurrences by
Trabalho<Pesquisa> ass{};
If not, just leave
Trabalho<Pesquisa> ass;
Unlike in Java, this does not mean that the variable will stay uninitialized. It's the C++ way to call a default (zero-argument) constructor.
Hi I am new in c++ and I make skeleton of program and I have some problems with destructors and constructors.
My head.cpp:
#include <iostream>
#include "set_char.hpp"
using namespace std;
int main()
{
set_char *z1 = new set_char(unsigned char *zbior[]);
delete z1;
return 0;
};
My set_char.hpp class file:
#define ROZMIAR_MAX 256
class set_char
{
unsigned char zbior[ROZMIAR_MAX];
public:
set_char(unsigned char *zbior[]);
~set_char(unsigned char *zbior[]);
int nalezy(unsigned char);
int licznosc();
void dodaj(unsigned char);
void usun(unsigned char);
};
And my set_char.cpp file:
#include "set_char.hpp"
#include <iostream>
#include <math.h>
using namespace std;
set_char(unsigned char *zbior[]);
~set_char(unsigned char *zbior[]);
void set_char::dodaj(unsigned char)
{
};
void set_char::usun(unsigned char)
{
};
int set_char::nalezy(unsigned char)
{
};
int set_char::licznosc()
{
};
Among others:
you should not add any parameters in destructors:
~set_char(unsigned char *zbior[]);
^^^^^^^^^^^^^^^^^^^^^^ --- remove it
When creating set_char you should provide pointer to your array, and not the actual parameter type:
set_char *z1 = new set_char(unsigned char *zbior[]);
^^^^^^^^^^^^^^^^^^^^^^
1
You did not define your Constructor and Destructor
You declared them both in your set_char.hpp
set_char(unsigned char *zbior[]);
~set_char(unsigned char *zbior[]);
However in set_char.cpp you re-declare them again without a return type. Defining a Constructor and Destructor outside of a class is illegal. Your compiler thinks they are functions and searches for a return type.
2
a Destructor may not have any arguments.
3
If you define an array as an argument in a Function or a Constructor or Destructor with brackets '[]', it may not be of variable length, thus it must be defined. If it is intended to be of variable length, it must be left out.
4
You are calling the constructor in a bad way using:
new set_char(unsigned char *zbior[]);
You already declared what arguments it takes, so hand it the arguments. A null pointer, for example.
The correct way to do it in set_char.hpp:
set_char(unsigned char *);
~set_char();
The correct way to do it in set_char.cpp:
set_char::set_char(unsigned char *zbior)
{
//Your definition
}
set_char::~set_char();
{
//Your definition
}
The correct way to do it in head.cpp:
set_char *z1 = new set_char(0x0);
Also side-note, usually using the define macro to define constants, is a C way. In C++ it is usually done with:
static const size_t ROZMIAR_MAX 256;
Second side-note. It is considered 'neater' code if you have your constants/functions and whatnot defined inside a namespace
I'm trying to create a member function that allows an user to set member array variables.
I've been looking everywhere but I can't find the problem in my code,
#include <string>
#include <iostream>
using namespace std;
class Employee
{
protected:
string name;
char ssn[11];
char id[5];
char hired[8];
public:
Employee(char ssn, char id, char hired); //Constructor
Employee(string name);
~Employee(); //Destructor
void setName(string n) { n = name; }
void setSSN(char i) { ssn = i; }
};
int main()
{
return 0;
}
Let's have a look at your setSSN function:
void setSSN(char i) { ssn = i; }
SNN, which most likely means social security number, doesn't consist of just one digit but 11, right? Then why would setSSN take as input only one character (digit) by (char i)? So setSSN function should rather take a string of characters containing SSN of the employee and that string should be of the same flavor as the ssn member variable of your Employee class in order to let you assign one string variable by another in the body of setSSN function. If you are already familiar with the string class of the C++ standard library, you should probably use that class for all your string storage and manipulation.
I'm having trouble declaring and initializing a char array. It always displays random characters. I created a smaller bit of code to show what I'm trying in my larger program:
class test
{
private:
char name[40];
int x;
public:
test();
void display()
{
std::cout<<name<<std::endl;
std::cin>>x;
}
};
test::test()
{
char name [] = "Standard";
}
int main()
{ test *test1 = new test;
test1->display();
}
And sorry if my formatting is bad, I can barely figure out this website let alone how to fix my code :(
If there are no particular reasons to not use std::string, do use std::string.
But if you really need to initialize that character array member, then:
#include <assert.h>
#include <iostream>
#include <string.h>
using namespace std;
class test
{
private:
char name[40];
int x;
public:
test();
void display() const
{
std::cout<<name<<std::endl;
}
};
test::test()
{
static char const nameData[] = "Standard";
assert( strlen( nameData ) < sizeof( name ) );
strcpy( name, nameData );
}
int main()
{
test().display();
}
Your constructor is not setting the member variable name, it's declaring a local variable. Once the local variable goes out of scope at the end of the constructor, it disappears. Meanwhile the member variable still isn't initialized and is filled with random garbage.
If you're going to use old-fashioned character arrays you'll also need to use an old-fashioned function like strcpy to copy into the member variable. If all you want to do is set it to an empty string you can initialize it with name[0] = 0.
Since you are using C++, I suggest using strings instead of char arrays. Otherwise you'd need to employ strcpy (or friends).
Also, you forgot to delete the test1 instance.
#include <iostream>
#include <string>
class test
{
private:
std::string name;
int x;
public:
test();
void display()
{
std::cout<<name<<std::endl;
}
};
test::test()
{
name = "Standard";
}
int main()
{
test test1;
test1.display();
std::cin>>x;
}
Considering you tagged the question as C++, you should use std::string:
#include <string>
class test
{
private:
std::string name;
int x;
public:
test();
void display()
{
std::cout<<name<<std::endl;
std::cin>>x;
}
};
test::test() : name("Standard")
{
}
c++11 actually provides two ways of doing this. You can default the member on it's declaration line or you can use the constructor initialization list.
Example of declaration line initialization:
class test1 {
char name[40] = "Standard";
public:
void display() { cout << name << endl; }
};
Example of constructor initialization:
class test2 {
char name[40];
public:
test2() : name("Standard") {};
void display() { cout << name << endl; }
};
You can see a live example of both of these here: http://ideone.com/zC8We9
My personal preference is to use the declaration line initialization because:
Where no other variables must be constructed this allows the generated default constructor to be used
Where multiple constructors are required this allows the variable to be initialized in only one place rather than in all the constructor initialization lists
Having said all this, using a char[] may be considered damaging as the generated default assignment operator, and copy/move constructors won't work. This can be solved by:
Making the member const
Using a char* (this won't work if the member will hold anything but a literal string)
In the general case std::string should be preferred