question about CPP programing

[eyalt]

hi, i tried to compile this program and the compiler gave me this massage: "invalid use of 'class circle1'.
im quiet new at progrming and i have no idea what i did wrong.
any help will be appricieted...

this is my code:
main:

#include <iostream>
#include <fstream>
#include "circle1.h"
#include "tri.h"
using namespace std;

int main()
{
    int x,y;
    circle1 r;
    cout<<"enter numbers";
    cin>>x>>y;
    r.circle1(x);
    return 0;
}

class:

#ifndef CIRCLE1_H_INCLUDED
#define CIRCLE1_H_INCLUDED

class circle1
{
    private:int r;
    public:
    void clch(int);
    void clcs(int);
    circle1(int);
    circle1();
};



#endif // CIRCLE1_H_INCLUDED

header:

#include <iostream>
#include <math.h>
#include <stdlib.h>
#include "circle1"
using namespace std;

circle1::circle1(int x)
{

    if(x<0)
    cout<<"the number you enterd is negative!";
    else
    {
    r=x;
    void clch(int x);
    void clcs(int x);
    }
}

void circle1::clch(int x)
{
    x=x*2*M_PI;
    cout<<"this is the hikef of the first circle: "<<x<<"\n";
}

void circle1::clcs(int x)
{
    x=2*M_PI*(pow(x,2));
    cout<<"this is the sheth of the first circle: "<<x<<"\n";

}