如何检索枚举类型变量中的元素？

Question

When the code is compiled, it doesn't show the values inserted to the enum variable in structure

This code only shows the keyboard input 0 or 1

#include<stdio.h>
#define Max_CHARS_NAME 100

struct gps_point{
    double latitude;
    enum latitude_pole {North,South} pole;
    double longitude;
    enum longitude {East,West} dire;
    char location_name[Max_CHARS_NAME];
}g;

int main(){
    char arr[Max_CHARS_NAME];
    int i = 0;

    printf("Enter location\n");
    scanf("%s", &g.location_name);  
    strcpy(arr,g.location_name);

    printf("Enter latitude\n");
    scanf("%lf", &g.latitude);

    printf("Enter latitude pole North - 0, South - 1\n");
    scanf("%d",&g.pole);

    //g.latitude_pole = g.pole;

    printf("Enter longitude dire East - 0, West - 1\n");
    scanf("%d", &g.dire);

    printf("Enter longitude\n");
    scanf("%s", &g.longitude);

    printf("%s is situated at (Latitude : %s %lf , Longitude: %s %lf). \n",arr,g.pole,g.latitude,g.dire,g.longitude);

    return 0;
}

Answer 1

See the below example,

enum week{Mon, Tue, Wed, Thur, Fri, Sat, Sun}; 

int main() 
{ 
    enum week day; 
    day = Wed; 
    printf("%d",day); 
    return 0; 
}  

Here we declare a variable day of type week and assign one(numerical) value in the list to the variable using a "string" but it isn't possible to do the other way.

Answer 2

This is equivalent to

enum latitude_pole {
  North = 0,
  South = 1
} pole;

This defines the variable pole whose possible values are North(0) and South(1).

It is equivalent to writing

enum latitude_pole {
  North = 0,
  South
} pole;

because in case you initialize one member the next one will be +1 (previous member).

In your code the missing of initialization will have it insert by default the value 0 for the first member and 1 for the second member.

Answer 3

If you don't give the enumeration constants any values, the compiler will do it silently.

The first one will always be given value 0 , and every following enumeration constant will get the value of previous constant + 1.

In your case {North,South} , North is guaranteed to be 0 and South guaranteed to be 1. The type of these enumeration constants is guaranteed to be 100% compatible with int .

Had you typed only some values explicitly, the rule where every constant getting the value of the previous + 1 is still applicable. So if you would do {North,South,East=5,West} , they would get the values 0, 1, 5, 6 .