CODEWITHSUNDEEP
c++arrayslistlinked-list
Brandon Ripley
Brandon Ripley

Reputation: 11

C++ Linked list creation - passing in an array

I am working on creating a linked list in c++, and I can't figure out how to pass an array as an argument in the constructor, or if thats even legal syntax.

This is the error I get: 

CheckTextFile.cpp: In constructor ‘Node::Node(char*, int)’:
CheckTextFile.cpp:19: error: incompatible types in assignment of ‘char*’ to ‘char [0u]’
CheckTextFile.cpp: In constructor ‘Node::Node(char*, int, Node*)’:
CheckTextFile.cpp:24: error: incompatible types in assignment of ‘char*’ to ‘char [0u]’

Here is my code: 

class Node{
public:
    int length;
    char data[];
    Node * next;
    Node(char x[], int y){
        data = x;
        length = y;
        next = NULL;
    }
    Node(char x[], int y, Node * z){
        data = x;
        length = y;
        next = z;
    }

};

Upvotes: 1

Views: 1656

Answers (4)

Rohit Vipin Mathews
Rohit Vipin Mathews

Reputation: 11787

class Node{
public:
    int length;
    char *ptr_data;  //pointer 
    Node * next;
    Node(char *x, int y){
        ptr_data = x;  //pointer assignment
        length = y;
        next = NULL;
    }
    Node(char *x, int y, Node * z){
        ptr_data = x;    //pointer assignment
        length = y;
        next = z;
    }
};

Upvotes: 0

Alok Save
Alok Save

Reputation: 206636

You are passing an pointer to the first element of the array, and actually that is correct.

The compiler is complaining about assignment inside the constructor: 

data = x;

You cannot assign arrays as such, not like objects, you will have to copy each element from the source array to the target array.
Either using a looping construct or using std::copy.

A trivial way(efficient would be to use std::copy) of doing so: 

Node(char x[], int y)
{
     for(int i = 0;i<y; ++i)
     { 
         data[i] = x[i];
     }
     length = y;
     next = 0;
}

Or Simply

std::copy(x,x+y,data);

And it will compile cleanly.

On a side note, you are much better off using std::string rather than using char arrays.

Upvotes: 1

dicaprio
dicaprio

Reputation: 733

First of all, in C++, you can't have an array of unspecified size. Also, you can use a pointer instead of an array or std:string.

Upvotes: 0

Greg Hewgill
Greg Hewgill

Reputation: 994599

Your argument passing is fine. However, your:

char data[];

declares an array with no size, so it's not surprising that the compiler refuses to generate code to put anything in there. Perhaps try:

std::string data;

This is assuming that your x[] represents a NUL-terminated C string.

After you do that, learn about the member initialisation syntax for constructors.

Upvotes: 3

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