动态数组更改内存地址位置

Question

I'm having a slight issue and not quite understanding the syntax for what I'm wanting to do. See below:

float* ParticleSystem::GetMinLifeTime()
{
    return &minLifeTime;
}

I'm wanting to declare a dynamic array and then change the value of element 0 to point to the minLifeTime memory location. MY attempt so far has been:

float* lifeTimeNumbers = new float[LIFETIME_STRINGS_SIZE];


lifeTimeNumbers[0] = *activeParticleSystem->GetMinLifeTime();

My understanding though is that I'm dereferencing the values when adding them to the array. This isn't what I'm wanting. I'm really wanting to change the memory location of lifeTimeNumbers[0] to the memory location returned by GetMinLifeTime(). Can I do such a thing?

Cheers

Answer 1

you can't change the address of [0] of the array as the array is basically ONE area of memory and not a number not individual pointers.

Your 'isssue' could be done using a **.. then you could have [0] store a pointer to the value

Answer 2

Your question is mostly about how to fix the problems with an approach Y to achieving X.

Where approach Y is really meaningless (this is known as an XY-problem ).

Instead of focusing on Y, do X directly:

#include <vector>

double ParticleSystem::minLifeTime() const
{
    return minLifeTime_;
}

int main()
{
    std::vector<double> lifeTimeNumbers;

    ParticleSystem activeParticleSystem = ...;
    lifeTimeNumbers.push_back( activeParticleSystem.minLifeTime() );
}

Answer 3

I'm really wanting to change the memory location of lifeTimeNumbers[0] to the memory location returned by GetMinLifeTime()

All you need to do is this:

float *lifeTimeNumbers = activeParticleSystem->GetMinLifetime();

Now you have a pointer which points to the first element of the array.

Answer 4

What you want is an array of pointers to floats rather than an array of floats. To achieve that you have to declare the array like this

float** lifeTimeNumbers = new float*[LIFETIME_STRINGS_SIZE];
lifeTimeNumbers[0] = activeParticleSystem->GetMinLifeTime();

but why not just using a vector container like this

std::vector<float*> vec;
vec.push_back(activeParticleSystem->GetMinLifeTime());