C language: enumerating knowledge points summary

Use the enumeration type declaration symbol name to represent the integer constant . Use enum keyword , You can create a new “ type ” And specify the values he can have （ actually ,enum Constant is int type , therefore , As long as it can be used int Type, you can use enumeration type ）. The purpose of enumerating types is to improve the readability of programs .

• Enumeration type

  You can use enumeration type declaration symbols to represent integer constants . Use enum keyword , You can create a new type and specify the values it can have （ actually ,enum Constant is int type , therefore , As long as it can be used int Type, you can use enumeration type ）. The purpose of enumerating types is to improve the readability of programs .

  enum spectrum {
        red,orange,yellow,green,blue,violet};
  enum spectrum color;
  

  int c;
  color = blue;
  if(color==red)
      ...;
  for(color=red;color<=violet;color++)
      ...;
  

• enum Constant
  From the perspective of Technology ,red,blue Wait until these enumerators are int Constant of type . When you declare an array , You can use enumeration constants to represent the size of the array , stay switch Statement can use enumeration constants as labels .

• Default value for enumeration

  By default , The values in the enumeration list are all from 0 Start .

  In the declaration of enumeration , You can specify integer values for enumeration constants

  enum feline {
        low=100,med=200,high=300};
  

  If you assign a value to only one enumeration constant , There is no assignment to the following enumeration constant , Then the following constants will be given subsequent values .

  enum feline {
        cat,lmj=100,jijia,lop};
  

  that cat The value of is 0,lmj The value of is 100,jijia The value of is 101,lop The value of is 102.