I need some explaining.

[lilthanos]

Hey guys. Good mornin.

I usually don't get stuck on these type of exercises but I didn't really understand how to go forward and backwards with numbers.

3 3 ( The first 3 is how many lines in a for(), the second one is the current channel)
5
7 (5,7,2 are the channels It needs to get trough.
2

Answers:
9 (How many channels it went trough)
DDDDKKKKK (D - up, K - down)

(code)
using namespace std;
//---------------------------------------
void howmany ( int n, int bkan, int &a );
int main ()
{
int n, bkan, a, k;

ifstream df ("TV.txt");
df >> n >> bkan; // 3 3
for ( int i = 0; i < n; i++)
{
df >> a; // 5 7 2
}

cout << k; // how many times
return 0;
}
void howmany ( int n, int bkan, int &a )
{
int k = 0;
for ( int i = 0; i < n; i++)
{
if ( bkan < a ) cout << "D" << endl;
else ( bkan <= a) cout << "K" << endl;
k++;
}
}
}
(/code)

If I have 3 then, it checks if its lower than 5 and it prints out D. But how can I make it that it would remember the letters and move on to the next number?
Any help would be appreciated.

[keskiverto]

"To remember" means to store data in variable(s). Since data is characters, it would make sense to store the sequence in std::string.

[lilthanos]

We haven't gotten learning strings yet but it asks us to do it with a void() function.
So I don't really know how to do strings but I know what they do in some way.

[keskiverto]

The string would be relatively easy to use: http://www.cplusplus.com/reference/string/string/operator+=/

What containers have you learned already?

[seeplus]

Possibly something like (without using a function or std::string):

#include <iostream>
#include <iomanip>
#include <sstream>

int main() {
	size_t N {};
	int init {};
	std::ostringstream oss;

	std::cin >> N >> init;

	for (size_t i {}; i < N; ++i) {
		int n {};

		std::cin >> n;

		if (n > init)
			oss << std::setw(n - init) << std::setfill('D') << 'D';
		else if (init > n)
			oss << std::setw(init - n) << std::setfill('K') << 'K';

		init = n;
	}

	std::cout << oss.str().size() << '\n' << oss.str() << '\n';
}

3 3
5 7 2
9
DDDDKKKKK

See http://www.cplusplus.com/reference/sstream/stringstream/

[deleted account xyzzy]

I don't really know how to do strings

https://www.learncpp.com/cpp-tutorial/an-introduction-to-stdstring/

There is also the C string, a char array.
https://www.learncpp.com/cpp-tutorial/c-style-strings/

And a reminder:

Please learn to use code tags, they make reading and commenting on source code MUCH easier.

How to use code tags: http://www.cplusplus.com/articles/jEywvCM9/

There are other tags available.

How to use tags: http://www.cplusplus.com/articles/z13hAqkS/

HINT: you can edit your post and add code tags.

Some formatting & indentation would not hurt either

[deleted account xyzzy]

A more in-depth look at std::string, starting at the beginning of Lesson 22 over at Learn C++:

https://www.learncpp.com/cpp-tutorial/stdstring-and-stdwstring/