header file question

[Ch1156]

Ok so i have a header file and i have this function in it:

#ifndef UNTIL_H_INCLUDED
#define UNTIL_H_INCLUDED

void until(int from, int until)
{
    from;
    until;

    for(from; from < until; from++)
    {
        cout << from +1 << endl;
    }
}

#endif // UNTIL_H_INCLUDED 

Now it needs std::cout but i have been told you should never put namespace in a header file and such, so how can i do this? I am going to put until in a namespace also, not sure if that will affect anything.

[AbstractionAnon]

You shouldn't be putting executable code in a header file.

However, if you're going to do that, then you need to qualify cout and endl with the std namespace.

    std::cout << from +1 << std::endl;

What's the purpose of lines 6 and 7? They don't do anything.

It's bad practice to name your arguments the same as your function (until).

[Ch1156]

Im making a namespace thoug so what should i put it in?

[Disch]

+1 @ AbstractionAnon


Plus, if your body is in a header file, the function must be marked as inline or else you'll get linker errors if you include in multiple files.

Also, you have some nonsense there....

#ifndef UNTIL_H_INCLUDED
#define UNTIL_H_INCLUDED

inline void until(int from, int until) // <- mark as inline
{
//    from; <- these 2 lines do nothing, get rid of them
//    until;

    for(/*from*/; from < until; from++)  <- that first 'from' also does nothing
    {
        std::cout << from +1 << std::endl; // <- std:: prefixes
    }
}

#endif // UNTIL_H_INCLUDED  

[Ch1156]

Ok i fixed everything you guys suggested but what type of file should i put them in? updated code:

#ifndef UNTIL_H_INCLUDED
#define UNTIL_H_INCLUDED

namespace userTools
{
    inline void until(int from, int until)
    {
        for(from; from < until; from++)
        {
            std::cout << from +1 << std::endl;
        }
    }
}

#endif // UNTIL_H_INCLUDED 

Main.cpp

#include <iostream>
#include "until.h"

using namespace std;
using namespace userTools;

/*Until Keyword
//
//The until function will loop through and output a
//vector or array from the first element all the way
//to the last element. If used with an integer it
//will output all the numbers from 0 to the last number.
//or it will start at the number specified.
*/

int main()
{
    int numbers = 50;

    until(0, numbers);
}

[Ch1156]

Ok now that the integer until loop is working i wanted to do it with an array but the problem is that if i have an array like this

int array_numbers[6] = {3,6,1,2,9,15};

the until function outputs this:

4 5 6 7 8 9 10 11 12 13 14 15

its supposed to output the array elements and it doesnt:

main

#include <iostream>
#include "until.h"

using namespace std;
using namespace userTools;

/*Until Keyword
//
//The until keyword will loop through and output a
//vector or array from the first element all the way
//to the last element. If used with an integer it
//will output all the numbers from 0 to the last number.
*/

int main()
{
    int numbers = 200;
    int array_numbers[6] = {3,6,1,2,9,15};

    //int_until(50, numbers);
    array_until(array_numbers[0], array_numbers[5]);
}

until.h

#ifndef UNTIL_H_INCLUDED
#define UNTIL_H_INCLUDED

namespace userTools
{
    inline void int_until(float int_startVar, float int_endVar)
    {
        for(int_startVar; int_startVar < int_endVar; int_startVar++)
        {
            std::cout << int_startVar + 1 << std::endl;
        }
    }

    inline void array_until(float array_startVar, float array_endVar)
    {
        for(array_startVar; array_startVar < array_endVar; array_startVar++)
        {
            std::cout << array_startVar + 1 << std::endl;
        }
    }
}

#endif // UNTIL_H_INCLUDED 

[Ch1156]

bump

[coder777]

the until function outputs this:

yes, the functions are designed to that.

if you want to output the array element you have to pass the array and the size of the array

[andywestken]

Or you can pass pointers to the beginning and end of the array (see below)

Notes:
1. I prefer int* to int[] as it makes it clearer (to me) that array params decay to a pointer. (It's also the form I encounter in API calls the most.)
2. In the begin/end pointer case I am following the C++ standard library approach of an inclusive start pointer and an exclusive (one past the end) end pointer.

Andy

#include <iostream>

// in #include "until.h"

namespace userTools
{
    inline void array_until_ptr_size(const int* pdata, size_t count)
    {
        for(size_t i = 0; i < count; ++i)
        {
            std::cout << " " << pdata[i];
        }
    }

    inline void array_until_ptr_ptr(const int* pbegin, const int* pend)
    {
        for( ; pbegin < pend; ++pbegin)
        {
            std::cout << " " << *pbegin;
        }
    }
}

using namespace std;
using namespace userTools;

/*Until Keyword
//
//The until keyword will loop through and output a
//vector or array from the first element all the way
//to the last element. If used with an integer it
//will output all the numbers from 0 to the last number.
*/

int main()
{
    int array_numbers[6] = {3, 6, 1, 2, 9, 15};
    const size_t size = sizeof(array_numbers) / sizeof(array_numbers[0]);

    cout << "array_until_ptr_size =";
    array_until_ptr_size(array_numbers, size);
    cout << endl;

    cout << "array_until_ptr_ptr  =";
    array_until_ptr_ptr(array_numbers, array_numbers + size);
    cout << endl;

    cout << endl;

    cout << "array_until_ptr_size:" << endl;
    for(int i = 0, s = (int)size; 0 < s; ++i, s -= 2)
    {
        cout << "i=" << i << ",s=" << s << " = ";
        array_until_ptr_size(&array_numbers[i], s);
        cout << endl;
    }

    cout << endl;

    cout << "array_until_ptr_ptr:" << endl;
    for(const int *b = array_numbers, *e = (b + size); b < e; ++b, --e)
    {
        cout << "b=" << b << ",e=" << e << " = ";
        array_until_ptr_ptr(b, e);
        cout << endl;
    }

    cout << endl;

    return 0;
}

[Ch1156]

Well I want to just be able to type array_until(value1, value2);

all your code completley defeats the purpose of what the function is meant to do. Which is make it simple to loop through values. I dont want to have to write all that out every time i want to use the until function.

[Disch]

what the function is meant to do. Which is make it simple to loop through values.

I'm a little confused as to the goal here. Are you're trying to recreate the for loop?

[andywestken]

I am not sure what your value1 and value2 are

For array

int data[] = {1, 2, 3};

you need to use either

array_until(data, 3); // with the function that takes a char* and an int

or

array_until(data, data + 3); // with the function that takes char*s for the begin and end

The key lines in my code above are 41 and 45; the later ones are just extra tests.

Andy

[vlad from moscow]

@Ch1156

If I have understood you mean the following function

void array_until( const int *a, int from, int until )
{
   for ( ; from < until; from++ )
   {
      std::cout << a[from] << std::endl;
   }
}