How to use a global variable as part of an array name

Question

I have four arrays:

int a1 [3] = { 10, 20, 30 }; 
int a2 [3] = { 10, 20, 30 }; 
int a3 [3] = { 10, 20, 30 };
int a4 [3] = { 10, 20, 30 };

I want to call array depending on a global variable:

int sys=1;

lets say:

int a1+sys; // this should gives array a2
int a1+2*sys; // this should gives array a3

How can I achieve this ?

Instead of individual 1D arrays, set up a single 2D array: int a[4][3] = { { 10, 20, 30 }, { 10, 20, 30 }, ...}; Now you can write a[sys]. — Igor Tandetnik
– Igor Tandetnik, Commented Jul 9, 2021 at 14:34
Maybe a 2D array: int a[4][3] = { {10,20,23}, {.... and then a[sys][x] ?? — Adrian Mole
– Adrian Mole, Commented Jul 9, 2021 at 14:35

eerorika · Accepted Answer · 2021-07-09 14:47:33Z

1

It seems that what you're looking for are arrays of arrays:

int a[][3] = {
    { 10, 20, 30 },
    { 10, 20, 30 },
    { 10, 20, 30 },
    { 10, 20, 30 },
}; 

auto& a2 = a[sys];
auto& a3 = a[2*sys];

answered Jul 9, 2021 at 14:47

eerorika

240k13 gold badges212 silver badges354 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1