Definition and use of enum in C language

Recently, I encountered the use of enumeration in my work , There are mainly two questions , How much space does enumeration variables occupy , Another
The first question is how many characters in the enumeration represent ？ With two questions, I compiled a small program to verify ：

#include <stdio.h>

enum  enum_type_enum
{
    
   RED,
   GREEN,
   BLUE,
   RED_BLUE=10,
   RED_GREEN
} enum_colour;


void main(void)
{
    
  unsigned char colour_id_test=0;
  printf(" Enumeration accounting %d byte \n",sizeof(enum_colour));
  while(1)
  {
    
	printf("please input the colour value !\n");
    scanf("%d",&colour_id_test);
    switch(colour_id_test)
	{
    
	case RED:
	   {
    
	     printf("colour is red\n");
	     break;
	   }
	case GREEN:
	   {
    
	     printf("colour is GREEN\n");
	     break;
	   }
	case BLUE:
	   {
    
	     printf("colour is BLUE\n");
	     break;
	   }
	case RED_BLUE:
	   {
    
	     printf("colour is RED_BLUE\n");
	     break;
	   }
	 case RED_GREEN:
	   {
    
	     printf("colour is RED_GREEN\n");
	     break;
	   }
	 default :
		 {
    
		  printf("the value is wrong\n");
		  break;
		 }
	}/*end of switch(colour_id_test)*/
  }/*end of while(1)*/
}/*end of main*/

Conclusion ：
1. Enumeration variables occupy 4 Bytes , All members share 4 Byte space , So is every member 4 Bytes of space , Only one member will exist at the same time .
2. The member of the first enumeration defaults to 0. The following members add 1, If there is a member assignment , Start with this member , The following members also add 1.