Print enum as a string

Question

I have actually an enum in c++:

class myClass
{
public:
    enum ExampleType
    {
       TEST1
       TEST2
       TEST3
       TEST4
    }
};

I would like to print the enum not as number but as String.. Actually it prints 0 .. 1 .. 2 .. 3 I would like it print TEST1 or TEST2 etc ...

I already try Switch case as :

 std::string type;
  switch (this->type)
    {
    case 0:   type = "TEST1";
    case 1:   type = "TEST2";
    case 2: type = "TEST3";
    case 3: type = "TEST4";
    }

then print type, but he don't go in the right case ..

How can it be possible ?

Add a `break;` after each assignment in the `case`. – Gene Jan 20 '14 at 20:50 — Gene, Jan 20 '14 at 20:50
Thx Gene, my bad, first time i use switch case – Laykker Jan 20 '14 at 20:54 — Laykker, Jan 20 '14 at 20:54

clcto · Accepted Answer · 2014-01-20T21:08:30.650

In C/C++, case statements fall through. You must use break to exit the switch statement. If your this->type is 0, then the code that is executed is:

type = "TEST1";
type = "TEST2";
type = "TEST3";
type = "TEST4";

What you want is:

switch( this->type )
{
case TEST1: type = "TEST1";
            break;
case TEST2: type = "TEST2";
            break;
//...
}

Or, if you have a function that is returning this value, simply return the value:

std::string type_string()
{
    switch( this->type )
    {
    case TEST1: return "TEST1";
    case TEST2: return "TEST2";
    //...
    default:    return std::string::empty();
    }
}

Note: (Since @DoxyLover's comment) I changed the switch to use the declared enum constants as you should use these instead. If someone added a TEST0 to the start of the enum, then the switch statement will still execute correctly, while your version would not.

In addition, use the enum values for the cases: `case TEST1:` instead of `case 0:` — DoxyLover, Jan 20 '14 at 21:04

score 2 · Answer 2 · answered Jan 20 '14 at 20:58

2

In addition to the other answers, you can also do something like this: (C99)

#include <ansi_c.h>

enum ExampleType
{
    TEST1,
    TEST2,
    TEST3,
    TEST4,
    TEST_MAX
};

const char string[TEST_MAX][10]={"TEST1","TEST2","TEST3","TEST4"};


int main(void)
{
    int i;
    for(i=0;i<TEST_MAX;i++)
    {
        printf("%d: %s\n", i, string[i]);   
    }

    return 0;
}

answered Jan 20 '14 at 20:58

ryyker

22,849
3
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Hell Yeah, worked too, there is so many possibilities ! – Laykker Jan 20 '14 at 20:58
Most of the time there is more than one way to skin a cat. (or something less gruesome if you prefer) – ryyker Jan 20 '14 at 21:00

score 1 · Answer 3 · answered Jan 20 '14 at 20:53

In switch-case statements, evaluation falls through between the cases. This is what makes it unique from if-else where the key word "else" assures that only one set of instructions is chosen. Add a break at the end of each case to prevent this as good practice.

Fiddling Bits · Answer 4 · 2014-01-20T21:02:09.277

1

If you know what you want to print at compile time, you can use the preprocessor like this:

Code

#define STRINGIFY(word) (#word)

int main(void)
{
    printf("%d %s\n", TEST2, STRINGIFY(TEST2)); 

    return 0;
}

Output

1 TEST2

Big But

However, this is really no different than doing this:

printf("%d TEST2\n", TEST2);

edited Jan 20 '14 at 21:02

answered Jan 20 '14 at 20:56

Fiddling Bits

8,712
3
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46

Wow, nice way too. Thx ! – Laykker Jan 20 '14 at 20:57
@Laykker It's probably not what you want. See my update. – Fiddling Bits Jan 20 '14 at 21:01

Print enum as a string

4 Answers4