how to print hex value of an enum to a string in c++

Question

How do I convert the hex value of the below enum to a string and store it in a variable.

enum {
    a      = 0x54,
    b,
    c
};

For example

auto value = a;
std::string value_as_hex = to_hex(a);

How do I write to_hex

There is no way to figure out if a enum constant was initialized with hex value or in some other way. Thus printing a enum value in hex is no different from printing an arbitrary variable in hex. — HolyBlackCat, Dec 19 '18 at 14:40
Whether you assign a value in decimal (84), hex (0x54) or octal (0124), the value will be stored the same internally. You can only choose to display this value in different ways. — flau, Dec 19 '18 at 14:47
Possible duplicate of [c++ cout hex values?](https://stackoverflow.com/questions/479373/c-cout-hex-values) — flau, Dec 19 '18 at 15:06
Hexadecimal 56 and decimal 86 (and octal 126, and binary 01010110, and Roman LXXXVI...) denote the same value, the only difference is in their textual form. — molbdnilo, Dec 19 '18 at 15:11
I can print the value in hex or octal with cout. how do I store (hex value) it in a variable to use further? — Anshika Verma, Dec 19 '18 at 15:44
Possible duplicate of [Integer to hex string in C++](https://stackoverflow.com/questions/5100718/integer-to-hex-string-in-c) — bradgonesurfing, Dec 19 '18 at 15:52

score 1 · Accepted Answer · answered Dec 19 '18 at 15:41

1

If you want to print the hex value of an enum you can use printf with the %x placeholder. For example

#include <cstdio>

enum Foo {
    a      = 0x54,
    b      = 0xA6,
    c      = 0xFF
};

int main() {
    Foo e;

    e = a;
    printf("%x\n",e);

    e = b;
    printf("%x\n",e);

    e = c;
    printf("%x\n",e);

}

the output of the program is

54
a6
ff

answered Dec 19 '18 at 15:41

bradgonesurfing

30,949
17
114
217

how do I store (hex value) it in a variable to use further? – Anshika Verma Dec 19 '18 at 15:46
e is a variable. When I write ``e = a`` the value of the enum `a` is stored in variable `e`. You can then use e sometime later. Please understand that you don't store a 'hex' value. When you write ``a = 0x54`` it is the same as writing ``a =84``. The computer has only one way of storing it. What do you want to do with this number later on? – bradgonesurfing Dec 19 '18 at 15:49

score 0 · Answer 2 · answered Dec 19 '18 at 16:13

0

How about the following solution?

std::ostringstream str;
str << std::hex << a;
auto x = str.str();

answered Dec 19 '18 at 16:13

andreee

4,459
22
42

score 0 · Answer 3 · answered Dec 19 '18 at 16:27

You could write your to_hex function to store the hex representation of the value in a string using stringstreams and IO manipulation :

#include <iostream>
#include <sstream>

std::string to_hex(const unsigned a) {
    std::stringstream ss;
    ss << "0x" << std::hex << a;
    return ss.str();
}

int main() {
    unsigned value = 0x1234;
    std::string value_as_hex = to_hex(value);

    std::cout << value_as_hex << "\n";
}

Output:

0x1234

how to print hex value of an enum to a string in c++

3 Answers3

Linked