C++: Modifying array values for const -

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consider following:

int a[2]; cin >> a[0] >> a[1];  const int d = a[1] - a[0];  cout << d << "\n";  a[1] = 5; a[0] = 2;  cout << d << "\n";

i'm bit confused now. why print same value d? why doesn't changing array values change value of d? @ point in time value of d determined , stored?

thanks!

the value of d determined in line assign it. can't change because values in expression used calculate changes, if weren't declared const. (few programming languages have variables work excel spreadsheet cells: cost of recomputing unpredictable significant.)

if want value of d change, have explicitly assign new value, compiler won't let unless remove const.


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