Can someone tell me what is wrong with this code?! visual studio tells the operand of * must be a pointer... (in line that we call operation)... can someone tell how exactly declaring an array of pointer to functions is? I'm really confused.
#include<iostream>
#include<conio.h>
using namespace std;
int power(int x)
{
return(x*x);
}
int factorial(int x)
{
int fact=1;
while(x!=0)
fact*=x--;
return fact;
}
int multiply(int x)
{
return(x*2);
}
int log(int x)
{
int result=1;
while(x/2)
result++;
return result;
}
//The global array of pointer to functions
int(*choice_array[])(int)={power,factorial,multiply,log};
int operation(int x,int(*functocall)(int))
{
int res;
res=(*functocall)(x);
return res;
}
int main()
{
int choice,number;
cout<<"Please enter your choice : ";
cin>>choice;
cout<<"\nPlease enter your number : ";
cin>>number;
cout<<"\nThe result is :"<<operation(number,(*choice_array[choice](number)));
}
The problem is that (*choice_array[choice](number))
isn't a function itself but a result of function call. Did you mean (*choice_array[choice])
?
operation takes a function as argument, but (*choice_array[choice](number))
is an int, cuz it's applying choice-array[choice]
to number
just do operation(number, choice_array[choice])
EDIT : don't want to say something wrong, but it seems to me that
*(choice_array[choice])
(choice_array[choice])
are the same, (meaning pointer to the function IS (can be used as a call to) the function, and you cant "dereference" it)
This call
operation(number, (*choice_array[choice](number)))
is invalid.
You have to supply a pointer to a function as second argument. Either write
operation(number, choice_array[choice] )
or
operation(number, *choice_array[choice] )
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