getting invalid errors for array type

Question

getting an invalid array type in the for loop not allowing me to fill the array sivalues. it wont poulate the array with x

int main () {
    double a,b,increment,para;
    int N;
    cout<< "enter values for (a,b,N)";
    cin>>a;
    cin>>b;
    cin>>N;
    increment= (b-a)/(N-1);
    double sivalues[N];
    for (double x=a;x<=b;x+=increment){
        sivalues[x]=si(x);
        cout<<"si("<<x<<") = "<< sivalues[x];
    }

    system("PAUSE"); return 0;

}

Unless I'm blind, increment is never initialized, which might be a problem. — Carcigenicate
– Carcigenicate, Commented Apr 2, 2017 at 4:23

Community · Accepted Answer · 2017-05-23 12:32:29Z

2

When you write sivalues[x], you are using a double as an array index. This is not valid, as it would make no sense to get the 2.5th element of an array, for instance. You would therefore need to cast your double into a int.

You could use the default cast (for example : sivalues[int(x)]=si(x);. Do note that this cast does not round, so if x is 5.99, it will still be converted to 5 (see C++: How to round a double to an int?)

edited May 23, 2017 at 12:32

CommunityBot

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answered Apr 2, 2017 at 4:42

Bettorun

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