stuck on function pointer

[technologist]

I keep getting the same error repeatedly and have tried to fix the second function pointer but no luck. Would appreciate some help here.

#include<iostream>

int foo(int a, bool(*n_ptr)(int a))
{

	std::cout<<(*n_ptr)(10);
	return a * a;
}

bool goo(int b)
{
	return b*b;
}

int pass_char(int(*char_ptr)(int a))
{
	std::cout<<"calling pass_char";

}

int main()
{

bool(*n_ptr)(int a);	//make pointer to function
n_ptr = goo; 			//point to a function
std::cout<<foo(10, n_ptr);	//dereference function

int(*char_ptr)(int a); 	//make pointer to another function<----difficulty here& onward
char_ptr = pass_char;	//	point it to function
//placeholder for function call
	return 0;
}

.\src\main.cpp:29:10: error: invalid conversion from 'int (*)(int (*)(int))' to 'int (*)(int)' [-fpermissive]
char_ptr = pass_char; // point it to function

[Ready4Droid]

int(*char_ptr)(int a); Type of function is int(*)(int)...
trying to set it to:
int pass_char(int(*char_ptr)(int a))... type of this is int(*)(int(*)(int))

Notice the difference?

I'm not really sure what you're trying to accomplish though.... but here is some code that compiles, if you are after something specific, let me know:

#include <iostream>
#include <conio.h>

//typedef our functions, it makes everything below much simpler to follow!
typedef bool(*Func1)(int);
typedef int(*Func2)(int);

int foo(int a, Func1 func)
{
	//Not sure why we return a bool value into an int??
	return func(a);
}

bool goo(int b)
{
	//Why are we returning a bool?
	return b*b;
}

int pass_char(int a, Func2 func)
{
	return func(a);
}

int goober(int b)
{
	return b + b;
}

int main()
{
	Func1 func1 = goo;
	std::cout << foo(10, func1) << std::endl;	//This simply prints the bool value?

	Func2 char_func = goober;
	std::cout << pass_char(5, char_func) << std::endl;	//This actually prints the value 5+5

	_getch();
	return 0;
}

[technologist]

Thx for your time

In answer to what I am trying to achieve here is a thought exercise. It has no other real utility than for learning more about passing function pointers through another function's parameter.

I cannot get char_ptr assigned to pass_char
I was able to get n_ptr assigned to goo

It seems this is where the problem lies. Thanks for the code, I am still studying it.

[Ready4Droid]

int(*char_ptr)(int a);
char_ptr = pass_char;

Notice how int(*char_ptr)(int) a); is defined as a function taking an integer, returning an integer. int()(int);
You are trying to assign your pass_char function to it, but look at it's definition:

int pass_char(int(*char_ptr)(int a))

It is NOT the same, it's taking a pointer to a function, which is fine if that's what you want, but you can't say int()(int) = int()(int(*)(int)), as the two types don't match.