' ' was not declared in this scope

Question

I was trying to implement this dynamic array thing and I ran into some problems When I try to compile it, the compiler tells me that bunch of my functions are not declared in this scope

here are the files

dynamicArray.h

#ifndef DYNAMICARRAY_H
#define DYNAMICARRAY_H

#include <ctime>
#include<iostream>
class dynamicArray{
public:
    dynamicArray();
    int * array_constructor(int *  &intPtr, int &size );
    int * array_resize(int * &intPtr, int& currSize, int& newSize);
    void array_destructor(int * &intPtr);
    void array_set(int* &intPtr, int &size);
};
#endif  // DYNAMICARRAY_H

dynamicArray.cpp

#include "dynamicArray.h"
#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;


int * array_constructor(int *  &intPtr, int &size ){
    if(intPtr != NULL){
        delete [] intPtr;
    }

    intPtr = new int[size];
    for (int i = 0; i < size; i++){
        intPtr[i] = i*i;
    }

    return intPtr;
}

int * array_resize(int * &intPtr, int& currSize, int& newSize){
    if(newSize == 0){
        delete [] intPtr;
        return NULL;
    }else if((newSize == currSize) || (newSize < 0)){
        return intPtr;
    }

    int * array = new int[newSize];
    for (int i = 0; i < newSize; i++){
        array[i] = i*i;
    }

    return array;
}

void array_destructor(int * &intPtr){
    delete [] intPtr;
    intPtr = NULL;
}

void array_set(int*& intPtr, int& size){
    srand(time(0));
    for (int i = 0; i < size; i++){
        intPtr[i] = rand();
    }
}

main.cpp

#include "dynamicArray.h"
#include <array>
#include <iostream>

using namespace std;

void print(int array[], int size){
    if(array == NULL){
        cout << "array is empty" << endl;
        return;
    }

    for(int i = 0; i < size; i++){
        cout << "array[" << i << "] = " << array[i] << endl;
    }
    cout << endl;
    return;
}

int main() {
    int *myArray = NULL;
    int size = 8;
    int newSize1 = 10;
    int newSize2 = 5;
    int newSize3 = -1;
    int finalSize = 1;

    myArray = array_constructor(myArray, size);
    print(myArray, size);

    myArray = array_resize(myArray, size, newSize1);
    print(myArray, newSize1);

    myArray = array_resize(myArray, newSize1, newSize2);
    print(myArray, newSize2);

    myArray = array_resize(myArray, newSize2, newSize3);
    print(myArray, newSize2);

    array_set(myArray, newSize2);
    print(myArray, newSize2);

    array_destructor(myArray);
    print(myArray, finalSize);

    return 0;
}

I tried putting int * dynamicArray::array_constructor(int * &intPtr, int &size ) instead, but no luck Did I do something wrong with the header file or in dynamicArray.cpp? This worked before, but I forgot how to do it.

main.cpp:27:46: error: 'array_constructor' was not declared in this scope — Leslie Zhou, Mar 15 '18 at 06:32
I recommend editing your question and copying the complete error message. — eyllanesc, Mar 15 '18 at 06:33
I strongly suggest you [pick one of these books](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) and go over C++ classes again. If you are trying to be object oriented here, it's not how one goes about it. — StoryTeller - Unslander Monica, Mar 15 '18 at 06:34

grek40 · Accepted Answer · 2018-03-15T06:44:20.783

1

If you want to implement the dynamic array management within a class, you need to qualify your method implementations with the class name.

dynamicArray.cpp

int * dynamicArray::array_constructor(int *  &intPtr, int &size ){
    if(intPtr != NULL){
    // ...

other member functions the same thing.

However, you don't really use your class in a class-like way at all. So you could consider turning your class into a namespace and implement the functions there (or in global scope):

dynamicArray.h

namespace dynamicArray // optional namespace
{
    int * array_constructor(int *  &intPtr, int &size );
    int * array_resize(int * &intPtr, int& currSize, int& newSize);
    void array_destructor(int * &intPtr);
    void array_set(int* &intPtr, int &size);
}

dynamicArray.cpp

namespace dynamicArray // optional namespace
{
    int * array_constructor(int *  &intPtr, int &size ){
        if(intPtr != NULL){

    // ... implement your functions like before
}

main.cpp - add namespace usage

//...
using namespace std;
using namespace dynamicArray;
//...

edited Mar 15 '18 at 06:44

answered Mar 15 '18 at 06:32

grek40

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I already tried that, didn't work – Leslie Zhou Mar 15 '18 at 06:34
1

@LeslieZhou Actually, the more I look into it I realize you don't really use you class at all in the main function. So everything class related is bound to fail. – grek40 Mar 15 '18 at 06:35
What do you mean by that? – Leslie Zhou Mar 15 '18 at 06:38
would it work if I don't have class dynamicArray{} in the header file? Just the functions instead – Leslie Zhou Mar 15 '18 at 06:40
@LeslieZhou if you place the functions into global scope your approach will need less tweaking. See my edit with a suggestion to place the functions into a namespace instead of a class. – grek40 Mar 15 '18 at 06:45
That works too.thanks – Leslie Zhou Mar 15 '18 at 06:47

' ' was not declared in this scope

1 Answers1