Here is my code. I try to fix it and I always obtain the same error: expected primary expression before 'int'.

in line 47, 55, 63, 80, 86.

And I've already tried this program in small pieces before and it works. It doesn't marked that error.

` #include

using namespace std;


int add (int a, int b)
{
int r;
r=a+b;
return (r);
}


int ssub (int a, int b)
{
int r;
r=a-b;
return (r);
}


int mult(int a, int b)
{
int r;
r=a*b;
return (r);
}


int menu(int a, int b){

int r;
char x;
cout <<"What do you want to do: \na.Adding \n s. Substract \n m. Multiply. \n. e. Exit"<<endl;
cin>>x;

switch (x){
case 'a':
cout << "Give a value for a"<<endl;
cin>>a;
cout <<"Give a value for b"<<endl;
cin>>b;
add (int a, int b); //aquí y en otras líneas me sale: expected primary expression before int.
break;

case 's':
cout << "Give a value for a"<<endl;
cin>>a;
cout <<"Give a value for b"<<endl;
cin>>b;
ssub (int a, int b);
break;

case 'm':
cout << "Give a value for a"<<endl;
cin>>a;
cout <<"Give a value for b"<<endl;
cin>>b;
mult (int a, int b);
break;

case 'e':
x='e';
break;

default:
cout<<"Wrong choice. Run the program again and choose another letter"<<endl;
break;
}

return r;

}

cout<<"The result is  " << menu (int a, int b)<<endl;


int main()
{

menu (int a, int b);

return 0;
}

`