Class or Template? Convert integers into decimal, octal, and hexadecimal.

[Arc]

Ok I started writting this as a class, then realized a template may be better.

What I need to do is take 3 numbers (10, 010, 0x10 for example) decimal, octal, and hexadecimal and then output the number in all 3 formats. If 0x10 was input then I would need to output that number in decimal, octal, and hexadecimal format.

Now I figure a template would be the best way to go since 3 different kinds of numbers will be getting input into the same function. But I am not sure how to handle the conversion of these numbers. I think there is something in the stream manipulation that can handle this, but I would appreciate some help figuring it out.

Also, I am not sure, but I think I would need to return an array from the function that held all three conversions of the number. I guess it would have to be a string array unless 0x10 (for example) can be held in a int array. This is also something I do not know how to do..I can do it in VB but not C++.

Any help is appreciated!

template<class T>
string convertInt( const T )
{

//convert numbers to dec, hex and oct values and return all 3


}//end convertInt 

[twanvl]

This is not somewhere you should use a template, since the numbers are always converted from strings to integers or the other way around.
In this case the easiest way would be to use the C sprintf/sscang functions, because they support the octal and decimal format:

#include <cstdio>
#include <string>

std::string numberInThreeFormats(const std::string& str) {
    char buffer[255]; // large enough to hold any number three times
    int number;
    std::sscanf(str.c_str(), "%i", number); // %i = integer in decimal, octal or hexadecimal
    std::sprintf(buffer, "%d, 0%o, 0x%x", number, number, number); // %d = decimal, %o = octal, %x = hexadecimal
    return buffer;
}

All this is also possible using C++ iostreams for example, but you would have to do more work yourself.

[Arc]

Yah I have to use Iostream in C++ . But thanks for the post.

[Arc]

So does anyone know how to tell if a number is a decimal, hex or oct using iostream?

I need to input a number and tell if its a decimal, hex or oct and if so return what it is...if it isn't then return an error.

That is easy enough if I can figure out how to tell if the input is any of those or not.


Thanks!

[twanvl]

You could first read it into a string, and then check if it starts with "0x" or "0".

[CornedBee]

cout << oct << number << hex << number << dec << number;

This is much work, how?

[Arc]

Well you see that only converts integers or doubles to into hex dec and oct.

I need to able to accept a hex dec or oct as input and then convert it to all three.

Since a hex (i.e. 0x10) cant be input as an integer or a double then it has to be a string. and those iostream functions do not work on strings.

[kedaman]

how about doing the base conversion manually?
i=last,int b=1,a=0;
while(i>first)a+=*i--*b*=e1;
while(a)*j--=a%e2,a/=e2;

where first and last points to the first and last element in the char array to be converted from base e1 to base e2 in the char array j.

[CornedBee]

Why do something manually that you already have?

[kedaman]

well depends, there are always special cases which can be optimised