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Call function use pointer


Call function use pointer

By : Ahmed739
Date : November 21 2020, 07:38 AM
fixed the issue. Will look into that further First of all: Your functions void my_int_func(int x) and void my_int_func2(int y) do not return anything (return type void). They just prompt the input parameters to stdout.
What you probably want is something like that
code :
#include <iostream>

using namespace std;

int my_int_func(int x)
{
  return x;
}

int my_int_func2(int x)
{
  return x;
}

void sum(int x, int y)
{
  std::cout << x << " + " << y << " = " << (x + y) << endl;
}

int main()
{
  int (*f1)(int) = *my_int_func;
  int (*f2)(int) = *my_int_func2;
  sum(f1(1),f2(2));
}


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c++ pointer to pointer and call function that receive pointer to pointer

c++ pointer to pointer and call function that receive pointer to pointer


By : Nikh
Date : March 29 2020, 07:55 AM
like below fixes the issue The question is how to call function that request pointer to pointer if we are already at the function that operate with pointer to pointer. I tried some variants but all of them compile with error (SIGSEGV) http://rextester.com/ZSW68923 , This code segment
code :
   int* ptr_int;
    *ptr_int = 10;
int main()
{
    int* ptr_int = new int( 10 );
    test_session ( &ptr_int );   

    std::cout << "Hello, world!\n";

    delete ptr_int;
}
How to call the function in derived class to process handle_post?(Function call missing argument list to create pointer)

How to call the function in derived class to process handle_post?(Function call missing argument list to create pointer)


By : Jim
Date : March 29 2020, 07:55 AM
like below fixes the issue You are trying to pass a member function to support. In order to call such a function the caller need the member function arguments and the pointer to the instance to call the function on.
However support expects a std::function, i.e. without the instance pointer. So you have to wrap the call into another callable which does not need to have the BaseClass instance pointer passed. You can do that with a lambda (or std::bind if you prefer):
code :
Listener.support( methods::POST,
    [this](http_request request){return HandlePost(request);} );

Listener.support( methods::POST,
    std::bind(&BaseClass::HandlePost, this, std::placeholders::_1) );
C/C++ How to hand over a const function pointer or a simple pointer in one function call

C/C++ How to hand over a const function pointer or a simple pointer in one function call


By : Ali Farhan
Date : March 29 2020, 07:55 AM
Hope this helps I have a function (func1) that gets as a parameter a const pointer. The value of this pointer is used for a second function (func2). Depending on a boolean I want to modify this value before handing it to func2 or not. If I have to modify it I allocate new memory to store the modified version of it. Because in reality the const int pointer is a big array, I don't want to copy it. I tried to solve it that way: , This works?
code :
void func1(const int* value, bool change)
{
    const int* valueToUse;
    int changedValue;

    if(change)
    {
        changedValue = (*value) + 1;
        valueToUse = &changedValue;
    }
    else
    {
        valueToUse = value;
    }

    func2(valueToUse);
}
function call from dll [expression preceding parentheses of apparent call must have (pointer-to-) function type]

function call from dll [expression preceding parentheses of apparent call must have (pointer-to-) function type]


By : user1971405
Date : March 29 2020, 07:55 AM
With these it helps getGreetings is a const char*, not a function, what you want is to use reinterpret_cast() instead to make it in a function and not a variable.
Pinvoke- to call a function with pointer to pointer to pointer parameter

Pinvoke- to call a function with pointer to pointer to pointer parameter


By : siva ranjani
Date : March 29 2020, 07:55 AM
I wish did fix the issue. You have described how the PosT looks like, but this is not enough. First, have to know what the function expects to be passed as the ***PosT argument, and only THEN you can think of invoking it from C++ or C# side.
I know that probably does not fit your wishes, but please look:
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