Clever Geek Handbook

How do I pass arrays as parameters in a constructor? C ++

I am trying to create a constructor to call a class in which 4 arrays are passed as parameters. I've tried using *,&

the array itself; however, when I assign values ​​in parameters to variables in the class, I get this error:

 call.cpp: In constructor ‘call::call(int*, int*, char*, char*)’:
 call.cpp:4:15: error: incompatible types in assignment of ‘int*’ to ‘int [8]’
 call.cpp:5:16: error: incompatible types in assignment of ‘int*’ to ‘int [8]’
 call.cpp:6:16: error: incompatible types in assignment of ‘char*’ to ‘char [14]’
 call.cpp:7:16: error: incompatible types in assignment of ‘char*’ to ‘char [14]’

I would appreciate your help in finding my error and help me fix it. here is my code:

.h file

#ifndef call_h
#define call_h
class call{
private:
    int FROMNU[8]; 
    int DESTNUM[8];
    char INITIME[14]; 
    char ENDTIME[14];

public:
    call(int *,int *,char *,char *);
};
#endif

.cpp file

call:: call(int FROMNU[8],int DESTNUM[8],char INITIME[14],char ENDTIME[14]){
    this->FROMNU=FROMNU;
    this->DESTNUM=DESTNUM;
    this->INITIME=INITIME;
    this->ENDTIME=ENDTIME;
}
+3


source to share


3 answers


Raw arrays are not assignable and are usually difficult to handle. But you can put an array inside struct

and assign or initialize that. Essentially what std::array

.

eg. You can do

typedef std::array<int, 8>   num_t;
typedef std::array<char, 14> time_t;

class call_t
{
private:
    num_t    from_;
    num_t    dest_;
    time_t   init_;
    time_t   end_;

public:
    call_t(
        num_t const&     from,
        num_t const&     dest,
        time_t const&    init,
        time_t const&    end
        )
        : from_t( from ), dest_( dest ), init_( init ), end_( end )
    {}
};


But this still lacks a significant abstraction, so this is just a technical solution.

To improve the situation, consider what, for example, num_t

really is. Is this a phone number? Then model it as such.

We also consider the use of standard library containers std::vector

and arrays char

, std::string

.

+4


source


Passing a raw array as an argument is possible in C ++.

Consider the following code:



template<size_t array_size>
void f(char (&a)[array_size])
{
    size_t size_of_a = sizeof(a); // size_of_a is 8
}

int main()
{
    char a[8];
    f(a);
}
+1


source


In C / C ++, you cannot assign arrays by doing this->FROMNU=FROMNU;

, thus your method won't work and is half your error.

The other half is that you are trying to assign a pointer to an array. Even if you pass arrays to a function, they decay to pointers to the first element, regardless of what you say in the definition.

0


source






More articles:


All Articles