C++, output of one digit after the decimal -

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i'm new in c++ , help. don't understand why i'm getting output of 1 digit after decimal on sum below. have tried solve no success.

int main() {     double alt, t;      t = 4.5;     // function calculating altitude on time.     alt = (-0.12)*pow(t, 4) +(12.0)*pow(t, 3) -(380.0)*pow(t, 2) +(4100.0)*t +220.0;     cout << alt << endl;     return 0; }

the default behaviour of cout print 6 significant digits of floating points. can change with:

cout.precision(10); cout << alt << endl;

which gives output:

12019.2925

which seems correct solution.

you should not try set precision higher 15, because precision limit of double type (typically). can use numeric_limits<double>::digits10 <limits> make sure precision have.


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