C++ / Arduino: dynamic int array
Solution 1
Your code as I'm writing this:
class myClass
{
public: MyClass(int size);
private:
int _intArray[];
};
The declaration of _intArray
is not valid C++: a raw array needs to have a size specified at compile time.
You can instead instead use a std::vector
:
class myClass
{
public:
MyClass( int size )
: intArray_( size ) // Vector of given size with zero-valued elements.
{}
private:
std::vector<int> intArray_;
};
Note 1: some compilers may allow your original code as a language extension, in order to support the "struct hack" (that's a C technique that's not necessary in C++).
Note 2: I've changed the name of your member. Generally underscores at the start of names can be problematic because they may conflict with names from the C++ implementation.
Cheers & hth.,
Solution 2
You should use a std::vector.
class myCLass {
public:
myClass(int size)
: intarray(size) {
for(int i = 0; i < size; i++) intarray[i] = 0;
}
private:
std::vector<int> intarray;
};
Solution 3
I'll try the following:
class myClass
{
public:
MyClass(int size);
~MyClass();
private:
int* _intArray;
};
MyClass::MyClass(int size) {
_intArray = new int[size];
for (int i=0; i<size; ++i) _intArray[i] =0; // or use memset ...
}
MyClass::~MyClass() {
delete[] _intArray;
}
Or, even better, use a STL vector
instead ...
Solution 4
You should really use vectors as others have suggested. A work-around could be as shown (in case you do not want to use memcpy or a loop).
This would be useful if you have a really huge array. Note that it would add a level of indirection to access the array.
class myClass
{
public:
myClass(){
mt = T(); // value initialize.
}
private:
struct T{
int _intArray[10];
} mt;
};
int main(){
myClass m;
}
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JNK
Updated on May 11, 2022Comments
-
JNK about 2 years
I'm writing a class for the Arduino. It's been going well so far, but I'm sort of stuck now...
I have declared an int array in my class
class myClass { public: MyClass(int size); private: int _intArray[]; };
When I initialize the class
MyClass myClass1(5)
I need the array to look like this {0,0,0,0,0}.My question: what do I need to do so that the array contains 'size' amount of zeros?
MyClass::MyClass(int size) { //what goes here to dynamically initialize the array for(int i=0; i < size; i++) _intArray[i] = 0; }
Edit: Following up on various replies below, Arduino does not include the standard library so unfortunately
std::vector
is not an option -
Admin over 13 yearswhy not ": intarray(size,0) {" ?
-
Puppy over 13 years@Oxsnarder: Meh, not really that versed in vector's constructors.
-
Cheers and hth. - Alf almost 13 yearsThe zeroing loop is not ncessary:
std::vector
guarantees to zero those elements.