error: invalid operands of types 'int [1]' and 'float' to binary 'operator*'

Question

I get an error when I run my code:

error: invalid operands of types 'int [1]' and 'float' to binary 'operator*'

Codeblocks is telling me that the error appears in front of the "ct = ... "?

My code:

#include <iostream>
#include <math.h>

using namespace std;
float dt = 0.01;
int p = 50;
float ct = 0;
int main()
{
 int state [5][1] = {5,5,0,100,0 };
 // cout << *state[3];

for (float i = 0; i < 10; i+dt){
ct = (state[0]+(2*state[4]/state[5])* sin(state[4]*dt/2)*cos(state[2+state[4])*dt/2);

    }

}

Answer 1

You declared state to be an array of 5 arrays of 1 int each. Since state is an array of arrays, state[i] is itself an array. So when you write something like, eg, state[4]*dt what you're trying to do here is multiply an array ( state[4] is an array of one int ) with a float ( dt is a float) . While you can multiply an int with a float , you cannot multiply an int[1] with a float (that's what the compiler is complaining about). You will either want to make sure to always access the right subelement of the array inside your array, eg, state[4][0] , or not make state an array of arrays in the first place…

Apart from that, there's also a typo in that line, check your brackets.