HEX to DEC

[4w7X92yv]

Hello
Does someone knows a good HEX to DEC converted written in c++?
I wrote one but it only works if user inputs a code and not when a code is programmed. (it has to work like:
int hex = ff; ... output is 255;
whitout having to insert a input

Best Regards
Joriek

#include <iostream>

int main()
{
int hex = 0;

std::cin >> std::hex >> hex;

std::cout << hex;
std::cout << std::endl;
system ("pause");
return 0;
}

[LB]

int x = 0xff;
std::cout << x;

The key here is the "0x" before the hex.

[4w7X92yv]

thanks :)

[4w7X92yv]

@L B
now if i have a int called Number (witch contains a HEX code 11223344)
how can i do it so it reads it as 0x11223344?
Number is recieved from other little programs

thanks

int number = 11223344;
int hex = 0xNumber;

std::cout << hex;

[LB]

No, the 0x thing only applies to text that you type as numbers, aka constants. It does not work for variable names, even if they are const.

Whether you use hex or decimal, it is all binary in the computer's memory - so you just need to specify how you want to interpret it:

1 2 3 4 5

int numA = 0xFF; int numB = 255; std::cout << numA << ' ' << numB << std::endl; std::cout << std::hex << numA << ' ' << std::hex << numB << std::endl;

255 255 ff ff

[4w7X92yv]

Is there no other way to convert that Number to dec? or to bin?

[LB]

There is no 'conversion', you're just interpreting the number differently when converting it to a string.

std::dec
std::hex
std::oct

http://www.cplusplus.com/reference/iostream/ see Manipulators.

There is not one for binary, but that should not be difficult for you.

[4w7X92yv]

but how can i interprete the variable Number as a binary code?
idk how to do that
i know, my knowledge of c++ if very limited
but i beg you, can you help me further
thanks

[Stewbond]

Whenever you write a number, the compiler just reads it as binary. Using a cout will just format it as decimal, scientific, hex, oct, etc.

If you write 71 the compiler will store this as: 0100 0111. <-- decimal
If you write 0x47 the compiler will store this as: 0100 0111. <-- hex
If you write 0107 the compiler will store this as: 0100 0111. <-- octal
If you write 'G' the compiler will store this as: 0100 0111. <-- ascii

Now just output it however you like.

If you write int num = ff; you'll get a compilation error that ff is not defined. You need to write this as int num = 0xff.

[Texan40]

std::bitset is fine for binary.

char c = 0xFF;
std::bitset<8> char_bs(c); // templated argument is the size in bits
std::cout << bs.to_string() << std::endl;

[4w7X92yv]

@Texan40
bs undeclared
how do i solve?

#include <iostream>
#include <bitset>

int main()
{

char c = 0xFF;
std::bitset<8> char_bs(c);
std::cout << bs.to_string() << std::endl;

system ("pause");
return 0;

}

[Stewbond]

Wait, are you saying that you want to output the binary value with cout? I've never seen std::bitset as mentioned above but whenever I want to look at stuff in binary, I just use hex. It's more professional and much easier to read than binary as you don't have to do as much counting. Just learn to count by 4s.

[4w7X92yv]

@Stewbond
i have to output the value as binary, so i can convert it to dec whit a IEEE754 single precision floating piont 32bit

[Stewbond]

You could write your own function if you like...

std::string Num2Bin(int num)
{
    std::string output;
    while(num/1 > 0)
    {
        if (num%2 == 1) output += '1';
        else            output += '0';
        num /= 2;
    }
    return output;
}

Edit: forgot to return the string

[4w7X92yv]

1 problem: input is 50, output is 010011 but it should be 110010, how can i change this?
and i guess its a dec to bin, it should be hex to bin

#include <iostream>
#include <bitset>

int main()
{

int num;   
std::cin >> num;

std::string Num2Bin(int num);
{
    std::string output;
    while(num/1 > 0)
    {
        if (num%2 == 1) output += '1';
        else            output += '0';
        num /= 2;
    }
    std::cout << output;
    std::cout << std::endl;
}

system ("pause");
return 0;

}

[Stewbond]

Whoa, you're not just outputing it, you are planning to operate on it? Then don't bother converting it to binary. It's already in binary in your compiler.

If you are manually writing bits, the following will be your best friends:

Getting a bit:

int num = ...;
bit1 = num & 0x00000001;
bit2 = num & 0x00000002;
bit7 = num & 0x00000040;
etc...

Setting a bit:

num = (bit1 & 0x1) << 0; // the 0x1 isn't nessesary, but safe
num = (bit2 & 0x1) << 1;
num = (bit7 & 0x1) << 7;
etc...

<< is the left bit-shift operator
>> is the right bit-shift operator
& is a bit-wise and
| is a bit-wise or
^ is a bit-wise xor

You can do anything you want with these.

Another example, if you want to extract the third byte of a value:
byte3 = (num & 0x00ff0000) >> 16;
If you want to ensure the 20th bit is 1:
num |= 0x00080000;
If you want to ensure the 23rd bit is 0:
num &= 0x00400000;

I hope you see the pattern and the power

[Stewbond]

Regarding the function above... my bad..., it's inversed. Just reverse the bits.

[4w7X92yv]

@Stewbond
Tomorrow ill post the things i need, the program that i already have and what still has to happen
Then ill hope someone comes whit a converter from HEX to BIN or from HEX to DEC.

[Stewbond]

Here this inverses the bits for you.

std::string Num2Bin(int num)
{
    std::string binary;
    while(num/1 > 0)
    {
        if (num%2 == 1) output += '1';
        else            output += '0';
        num /= 2;
    }

    // Fill the output with ANYTHING for now (just to allocate memory to it)
    std::string output;
    output.reserve((int)(log(num)/log(2))+1);

    // Inverse the bits
    for (int i = 0; i < binary.size(); i++)
        output[i] = binary[binary.size()-(i+1)];

    return output;
}

Now just use it like this:

1 2 3 4

cout << Num2Bin(25) << endl; cout << Num2Bin(0x75) << endl; cout << Num2Bin(032) << endl; cout << Num2Bin('A') << endl;

11001 1110101 11010 1000001

[Texan40]

Sorry, I'm just sloppy and impatient sometimes. My code should have been:

#include <iostream>
#include <bitset>

int main()
{
  char c = 0xFF;
  std::bitset<8> char_bs(c);
  std::cout << char_bs.to_string() << std::endl;
  return 0;
}