数字常量之前的预期标识符

Question

我将此代码用作DFA确定性有限自动机，甚至可以接受1或0的输入

#include <stdio.h> 
#define TOTAL_STATES 2
#define FINAL_STATES 1
#define ALPHABET_CHARCTERS 2
#define UNKNOWN_SYMBOL_ERR 0
#define NOT_REACHED_FINAL_STATE 1
#define REACHED_FINAL_STATE 2
enum DFA_STATES{q0,q1,q2,q3};
enum input{0,1};
int Accepted_states[FINAL_STATES]={q0};
char alphabet[ALPHABET_CHARCTERS]={'0','1'};
int Transition_Table[TOTAL_STATES][ALPHABET_CHARCTERS];
int Current_state=q0;
void DefineDFA()
{
    Transition_Table[q0][0] = q3;
    Transition_Table[q0][1] = q1;
    Transition_Table[q1][0] = q2;
    Transition_Table[q1][1] = q0;
    Transition_Table[q2][0] = q1;
    Transition_Table[q2][1] = q3;
    Transition_Table[q3][0] = q0;
    Transition_Table[q3][1] = q2;
}
int DFA(char current_symbol)
{
int i,pos;
    for(pos=0;pos<ALPHABET_CHARCTERS; pos++)
        if(current_symbol==alphabet[pos])   
            break;//stops if any character other than a or b
    if(pos==ALPHABET_CHARCTERS)
         return UNKNOWN_SYMBOL_ERR;
    for(i=0;i<FINAL_STATES;i++)
 if((Current_state=Transition_Table[Current_state][pos])
==Accepted_states[i])
            return REACHED_FINAL_STATE;
    return NOT_REACHED_FINAL_STATE;
}
int main(void)
{
    char current_symbol;
    int result;
    DefineDFA();    //Fill transition table
    printf("Enter a string with 'a' s and 'b's:n Press Enter Key to stopn");

    while((current_symbol=getchar())!= 'n')
        if((result= DFA(current_symbol))==UNKNOWN_SYMBOL_ERR)
            break;
    switch (result) {
    case UNKNOWN_SYMBOL_ERR:printf("Unknown Symbol %c",
  current_symbol); 
 break;
    case NOT_REACHED_FINAL_STATE:printf("Not accepted"); break;
    case REACHED_FINAL_STATE:printf("Accepted");break;
    default: printf("Unknown Error");
    }
    printf("nnn");
    return 0;
}

我收到此错误10：15：错误：数字常量之前的预期标识符 10：15：错误：数字常量之前的预期"}" 10：15：错误：数字常量之前的预期非限定 ID 10：18：错误："}"标记之前的预期声明

Answer 1

枚举项必须是名称而不是值

enum input{AAA,BBB};

或

enum input{AAA=0,BBB};

或

enum input{AAA=0,BBB=1};

Answer 2

你的行：

enum input{0,1};

使用整数作为枚举值。这是不允许的。像这样：

enum input {n0, n1};

很好。使用枚举的全部意义在于，可以使用描述性标题代替数字。