Question

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Easy way to use variables of enum types as string in C?

Is there any elegant way to convert a user input string to an ENUM value is straight C, besides the manual way.

A simplified example of calling a function that takes an ENUM as an argument:

enum = {MONDAY,TUESDAY,WEDNESDAY};

...

//Get user to enter a day of the week from command line
...

//Set the work day according to user input
if (strcmp(user_input,"MONDAY")==0){
   SET_WORK_DAY(MONDAY);
} else if (strcmp(user_input,"TUESDAY")==0){
  SET_WORK_DAY(TUESDAY);
}
...

Thanks

Answer 1

$ cat wd.c
#include <stdio.h>

#define mklist(f) \
    f(MONDAY) f(TUESDAY) f(WEDNESDAY)

#define f_enum(x) x,
#define f_arr(x) {x, #x},

enum weekdays { mklist(f_enum) WD_NUM };

struct { enum weekdays wd; char * str; } wdarr[] = { mklist(f_arr) };

int main(int argc, char* argv[]) {
    int i;
    for (i=0; i < sizeof(wdarr)/sizeof(wdarr[0]); i++) {
        if (strcmp(argv[1], wdarr[i].str) == 0) {
            printf("%d %s\n", wdarr[i].wd, wdarr[i].str);
            return 0;
        }
    }
    printf("not found\n");
    return 1;
}
$ make wd
cc     wd.c   -o wd
$ ./wd MONDAY
0 MONDAY
$ ./wd TUESDAY
1 TUESDAY
$ ./wd FOODAY
not found

is my favorite way to do such things. This ensures that no consistency errors can occur between the enum and the mapping array.