Re: How to find number of times certain conditions happened in an array?

From:
terminator <farid.mehrabi@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Mon, 26 Nov 2007 03:39:35 -0800 (PST)
Message-ID:
<30da438a-e21b-4ec2-9638-896b6e80e681@s12g2000prg.googlegroups.com>
On Nov 26, 1:18 pm, lightai...@gmail.com wrote:

Dear Gurus,

I would like to implement a function that computes the number of times
a certain condition is met in a global array.

For example, I have an global array of size 500.
float array[500];

I have a function that finds the maximum of an array of size 50.
bool findMax50(float input[])

Next, I want to implement a function that can do the following;

Sum( findMax50(array), period)
If period is 20, then this function will start at the last element of
the global array and will return 1 if this element is a maximum among
the 50 elements it covers. Then, it moves on to the (last -1)th
element all the way to (last-20)th element. The Sum() function will
sum up the number of times maximum happened.

My greatest difficulty lies in how one can input a function as a
parameter into another function.


though as usual I cant make heads or tials of a post the answer to
your qustion:

Can some Guru advise?


Is:

You can use a function pointer:

typedef ret_type (*funcptr)(param_types);
ret_type foo(param_types);
funcptr fptr=&foo;

alternatively you can use functioniods:

class my_functioniod_base{
public:
    virtual ~my_functioniod_base()=0;
    ret_type operator()(param_types) const =0;
};

struct Tfoo:
    public my_functioniod_base
{
    ret_type operator()(param_typs) const{/*define it here.*/};
};

Tfoo foo;

my_functioniod_base & fref=foo;
fref(params);//runs Tfoo::operator().

you can do a little template work too:

template<typename pred>
void run(pred p){
    p();
};

void f();

run(&f);

have a look at the standard <algorithm> and <functional> headers too;
interesting tools you can find there.

yours,
FM.

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