C 枚举不返回未指定的值

标签 c enumeration

我正在创建一个程序来将编程语言的非终结符与终结符分开。枚举器跟踪非终结符的标记名称。非终结符 ID 设置为 0，所有其他 ID 均在其后枚举(理应如此)。然而，当程序找到非终结符时，它会打印一个奇怪的值 1953167781，尽管有些结果确实为 0。那些看起来像 1953... 的值的顺序如下:open int num = 7，num 是非终结符。 num 不被视为 0，而是被视为 1953167781。不过，如果它是这样的声明:guarded class test{}，则非终结符 test 为 0，而不是 1953167781。这种现象是否有可能的原因？提前感谢您的反馈!下面是输出图片和所发生过程的示例。

enter image description here

编辑

例如，让我们创建 header 来保存我们的声明:

#ifndef __TOK_H__
#define __TOK_H__

#define MAX (1024)

typedef enum {
    ID = 0,OPEN,CLOSED,GUARDED,ARTIFICIAL,STATIC,GLOBAL,CONT,SUPER,INT,FLOAT,CHAR,STRING,
    BOOL,COLLECTION,CLASS,FUNCT,METHOD,STRUCT,ENUM,IF,ELSE,_OR_,DO,UNTIL,UNLESS,FOR,
    FOREACH,IN,TRY,CATCH,EXCEPTION,RETURN,SKIP,BREAK,TERM,NEW,CALL,TRU,FALS,NIL,
    INUMBER,FNUMBER,VCHAR,VSTRING,UNDEF,LT,GT,LE,GE,EQ,NE,AND,OR,ADD,ADDE,INCRE,SUB,SUBE,
    DECRE,MULT,MULTE,DIV,DIVE,MOD,MODE,EX,EXE,INC,ASI,NOT,INHER,DOT,COM,LP,RP,LB,RB,LBR,
    RBR,APO,QUO,SEMCO,EOFT,NAT
} tokentype;

typedef struct {
    char str[MAX];
    tokentype type;
} token;

void sscan(FILE *);
token generate(FILE *fp);

#endif

这也是:

#ifndef __RESERVED_H__
#define __RESERVED_H__

char *keywords[] = { //40 keywords/reserved words
    "open","closed","guarded","artificial","static","global","cont","super",
    "int","float","char","string","bool","collection","class","funct","method",
    "struct","enum","if","else","or","do","until","unless","for","foreach","in",
    "try","catch","exception","return","skip","break","term","new","call","true",
    "false","null",
};
char *relative_operators[] = { //8 relops
    "<",">","<=",">=","==","!=","&&","||",
};
char operators[6] = { //6 operators
    "+-*/%^",
};
char delimeters[11] = { //11 delimeters
    ".,(){}[];'\"",
};
char unique_operators[] = { //5 unops
    "#!&|="
};

#endif

然后是(虽然效率不高)扫描仪和分离器:

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "reserved.h"
#include "tok.h"

int linenum = 1;
char ch;
token TOKEN;

int isLangPunct(char ch);
int isKEY(char *word);
int isDELIM(char ch);
int isRELOP(char ch);
int isUNIQUE(char ch);
int isOPERA(char ch);
tokentype getKey(char *word);
tokentype getDel(char ch);

void sscan(FILE *fp) {
    while ((ch = fgetc(fp)) != EOF) {
        if (ch == '\n') {
            linenum++;
            continue;
        } else if (isLangPunct(ch) || isalnum(ch) || isspace(ch)) {
            continue;
        } else {
            fprintf(stderr, "Undefined character: %c at line %d.\n", ch, linenum);
        }
    }
    rewind(fp); linenum = 1;
    do {
        generate(fp);
    } while (TOKEN.type != EOFT);
}
int isLangPunct(char ch) {
    int r = 0;
    if (ch == '#' || ch == '|' || ch == '&' || ch == '=' || ch == '%' ||
        ch == '!' || ch == '+' || ch == '-' || ch == '*' || ch == '/' ||
        ch == '.' || ch == ',' || ch == '(' || ch == ')' || ch == ';' ||
        ch == '{' || ch == '}' || ch == '[' || ch == ']' || ch == '\'' ||
        ch == '"' || ch == '<' || ch == '>' || ch == '^') 
    {
        r = 1;
    } return r;
}
token generate(FILE *fp) {
    char *word = malloc(sizeof(char) * MAX);
    char *number = malloc(sizeof(char) * MAX);
    int wi = 0, ni = 0;
    while((ch = fgetc(fp)) != EOF) {
        if (ch == '\n') {
            linenum++; continue;
        } else if (ch == '\t' || ch == ' ' || ch == '\r') {
            continue;
        } else if (isalpha(ch)) {
            do {
                word[wi++] = ch;
            } while(isalpha(ch = fgetc(fp)));
            word[wi] = '\0';
            wi = 0;
            strcpy(TOKEN.str, word);
            if (isKEY(word)) {
                TOKEN.type = getKey(word);
            } else {
                TOKEN.type = ID;
            }
            fseek(fp, -1, SEEK_CUR);
            printf("%d ", (int)TOKEN.type);
            return TOKEN;
        } else if (isdigit(ch)) {
            do {
                number[ni++] = ch;
            } while(isdigit(ch = fgetc(fp)));
            if (ch == '.') {
                do {
                    number[ni++] = ch;
                } while(isdigit(ch = fgetc(fp)));
                TOKEN.type = FNUMBER;
            } else {
                TOKEN.type = INUMBER;
            }
            number[ni] = '\0';
            ni = 0;
            strcpy(TOKEN.str, number);
            printf("%s ", TOKEN.str);
            fseek(fp, -1, SEEK_CUR);
            return TOKEN;
        } else if (isDELIM(ch)) {
            TOKEN.type = getDel(ch);
            char *str = &ch;
            //working on getting strings and chars to have
            //their own value types
            strcpy(TOKEN.str, str);
            printf("%s ", TOKEN.str);
            return TOKEN;
        } else if (isRELOP(ch) || isUNIQUE(ch)) {
            switch (ch) {
                case '<':
                    if ((ch = fgetc(fp)) == '=') {
                        TOKEN.type = LE;
                        strcpy(TOKEN.str, "<=");
                    } else {
                        TOKEN.type = LT;
                        strcpy(TOKEN.str, "<");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '>':
                    if ((ch = fgetc(fp)) == '=') {
                        TOKEN.type = GE;
                        strcpy(TOKEN.str, ">=");
                    } else {
                        TOKEN.type = GT;
                        strcpy(TOKEN.str, ">");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '=':
                    if ((ch = fgetc(fp)) == '=') {
                        TOKEN.type = EQ;
                        strcpy(TOKEN.str, "==");
                    } else {
                        TOKEN.type = ASI;
                        strcpy(TOKEN.str, "=");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '!':
                    if ((ch = fgetc(fp)) == '=') {
                        TOKEN.type = NE;
                        strcpy(TOKEN.str, "!=");
                    } else {
                        TOKEN.type = NOT;
                        strcpy(TOKEN.str, "!");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '&':
                    if ((ch = fgetc(fp)) == '&') {
                        TOKEN.type = AND;
                        strcpy(TOKEN.str, "&&");
                    } else {
                        fprintf(stderr, "Token Error: & missing at line %d.\n", linenum);
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '|':
                    if ((ch = fgetc(fp)) == '|') {
                        TOKEN.type = OR;
                        strcpy(TOKEN.str, "||");
                    } else {
                        TOKEN.type = INHER;
                        strcpy(TOKEN.str, "|");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '#':
                    TOKEN.type = INC;
                    strcpy(TOKEN.str, "#");
            }
            printf("%s ", TOKEN.str);
            return TOKEN;
        } else if (isOPERA(ch)) {
            switch (ch) {
                case '+':
                    if ((ch = fgetc(fp)) == '+') {
                        TOKEN.type = INCRE;
                        strcpy(TOKEN.str, "++");
                    } else if (ch == '=') {
                        TOKEN.type = ADDE ;
                        strcpy(TOKEN.str, "+=");
                        fseek(fp, -1, SEEK_CUR);
                    } else {
                        TOKEN.type = ADD ;
                        strcpy(TOKEN.str, "+");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '-':
                    if ((ch = fgetc(fp)) == '-') {
                        TOKEN.type = DECRE;
                        strcpy(TOKEN.str, "--");
                    } else if (ch == '=') {
                        TOKEN.type = SUBE;
                        strcpy(TOKEN.str, "-=");
                        fseek(fp, -1, SEEK_CUR);
                    } else {
                        TOKEN.type = SUB;
                        strcpy(TOKEN.str, "-");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '*':
                    if ((ch = fgetc(fp)) == '=') {
                        TOKEN.type = MULTE;
                        strcpy(TOKEN.str, "*=");
                    } else {
                        TOKEN.type = MULT;
                        strcpy(TOKEN.str, "*");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '/':
                    if ((ch = fgetc(fp)) == '=') {
                        TOKEN.type = DIVE;
                        strcpy(TOKEN.str, "/=");
                    } else if (ch == '/') {
                        do {
                            continue;
                        } while ((ch = fgetc(fp)) != '\n');
                    } else {
                        TOKEN.type = DIV;
                        strcpy(TOKEN.str, "/");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '%':
                    if ((ch = fgetc(fp)) == '=') {
                        TOKEN.type = MODE;
                        strcpy(TOKEN.str, "%=");
                    } else {
                        TOKEN.type = MOD;
                        strcpy(TOKEN.str, "%");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
                case '^':
                    if ((ch = fgetc(fp)) == '=') {
                        TOKEN.type = EXE;
                        strcpy(TOKEN.str, "^=");
                    } else {
                        TOKEN.type = EX;
                        strcpy(TOKEN.str, "^");
                        fseek(fp, -1, SEEK_CUR);
                    } break;
            }
            printf("%s ", TOKEN.str);
            return TOKEN;
        }
    }
    free(word);
    free(number);
    TOKEN.type = EOFT;
    strcpy(TOKEN.str, "\0");
    printf("%s ", TOKEN.str);
    return TOKEN;
}
int isKEY(char *word) {
    int r = 0;
    for (int i = 0; i < 40; i++) {
        if (*word == *keywords[i]) {
            r = 1;
        }
    }
    return r;
}
int isDELIM(char ch) {
    int r = 0;
    for (int i = 0; i < 11; i++) {
        if (ch == delimeters[i]) {
            r = 1;
        }
    }
    return r;
}
int isRELOP(char ch) {
    int r = 0;
    if (ch == '<' || ch == '>') {
        r = 1;
    }
    return r;
}
int isUNIQUE(char ch) {
    int r = 0;
    for (int i = 0; i < 5; i++) {
        if (ch == unique_operators[i]) {
            r = 1;
        }
    }
    return r;
}
int isOPERA(char ch) {
    int r = 0;
    for (int i = 0; i < 6; i++) {
        if (ch == operators[i]) {
            r = 1;
        }
    }
    return r;
}
tokentype getKey(char *word) {
    tokentype type;
    if (!strcmp(word, "open")) { type = OPEN; }
    else if (!strcmp(word, "closed")) { type = CLOSED; }
    else if (!strcmp(word, "guarded")) { type = GUARDED; }
    else if (!strcmp(word, "artificial")) { type = ARTIFICIAL; }
    else if (!strcmp(word, "static")) { type = STATIC; }
    else if (!strcmp(word, "global")) { type = GLOBAL; }
    else if (!strcmp(word, "cont")) { type = CONT; }
    else if (!strcmp(word, "super")) { type = SUPER; }
    else if (!strcmp(word, "int")) { type = INT; }
    else if (!strcmp(word, "float")) { type = FLOAT; }
    else if (!strcmp(word, "char")) { type = CHAR; }
    else if (!strcmp(word, "string")) { type = STRING; }
    else if (!strcmp(word, "bool")) { type = BOOL; }
    else if (!strcmp(word, "collection")) { type = COLLECTION; }
    else if (!strcmp(word, "class")) { type = CLASS; }
    else if (!strcmp(word, "funct")) { type = FUNCT; }
    else if (!strcmp(word, "method")) { type = METHOD; }
    else if (!strcmp(word, "struct")) { type = STRUCT; }
    else if (!strcmp(word, "enum")) { type = ENUM; }
    else if (!strcmp(word, "if")) { type = IF; }
    else if (!strcmp(word, "else")) { type = ELSE; }
    else if (!strcmp(word, "or")) { type = _OR_; }
    else if (!strcmp(word, "do")) { type = DO; }
    else if (!strcmp(word, "until")) { type = UNTIL; }
    else if (!strcmp(word, "unless")) { type = UNLESS; }
    else if (!strcmp(word, "for")) { type = FOR; }
    else if (!strcmp(word, "foreach")) { type = FOREACH; }
    else if (!strcmp(word, "in")) { type = IN; }
    else if (!strcmp(word, "try")) { type = TRY; }
    else if (!strcmp(word, "catch")) { type = CATCH; }
    else if (!strcmp(word, "exception")) { type = EXCEPTION; }
    else if (!strcmp(word, "return")) { type = RETURN; }
    else if (!strcmp(word, "skip")) { type = SKIP; }
    else if (!strcmp(word, "break")) { type = BREAK; }
    else if (!strcmp(word, "term")) { type = TERM; }
    else if (!strcmp(word, "new")) { type = NEW; }
    else if (!strcmp(word, "call")) { type = CALL; }
    else if (!strcmp(word, "true")) { type = TRU; }
    else if (!strcmp(word, "false")) { type = FALS; }
    else if (!strcmp(word, "null")) { type = NIL; }
    return type;
}
tokentype getDel(char ch) {
    tokentype type;
    if (ch == '.') { type = DOT; }
    if (ch == ',') { type = COM; }
    if (ch == '(') { type = LP; }
    if (ch == ')') { type = RP; }
    if (ch == '{') { type = LB; }
    if (ch == '}') { type = RB; }
    if (ch == '[') { type = LBR; }
    if (ch == ']') { type = RBR; }
    if (ch == '"') { type = QUO; }
    if (ch == '\'') { type = APO; }
    if (ch == ';') { type = SEMCO; }
    return type;
}

在与上述相同的文件中，main() 能够打开文件并读取它，将文件流发送到 sscan(FILE *)。最后一段是一个示例文件:

# call Sys;
# call SysIO;

static int num = 7;
cont global float fl = 12.895;
cont char letter = 'h';

collection Program {
    cont closed string aswkey = "abdcbabcdabdbcdab";
    open class quiz {
        bool decision = true;
        artificial method.study (int time) {};
        open quiz() {
            //do something
        };
    };
    class test | quiz {
        bool descision;
        super method.study (int time) {
            if (decision == true) {
                //do something
            } or if (time == 0) {
                //do something
            } else {
                //do nothing
            };
            time = 50;
        };
        guarded test (bool n) {
            descision = n;
        };
    };
    funct.Enter () {
        quiz Quiz = new quiz();
        test Test = new test(false);
        Test.study(60);
        if (something != this) {
            //do something
        };
        term;
    };
};

最佳答案

为了了解出了什么问题，让我们看看发生了什么。在 getKey(word)函数，当一个单词被发送到那里与关键字进行比较时，它将返回 tokentype type到TOKEN.type声明。但是，如果该单词与任何比较都不匹配，那么它仍然只返回一次作为 type 的变量。我的电脑上的地址是 1953167781。因此，通过向 getKey(word) 添加最后的 else 语句其中设置 tokentype type到 ID，它将所有非终结符与 ID 匹配。然而，这并不能解释为什么像 Sys 这样的词和SysIO也没有变成1953167781。而且这有点令人困惑if(isKEY(word))无法返回 false，它似乎总是返回 true。尽管它必须返回 false 才能转到 else 语句，该语句将有效地将所有非终结符设置为 ID。但这仍然提出了一个我们不会讨论但应该思考的问题:为什么像 Sys 这样的非终结符会出现？和SysIO成为 ID 的(请注意 getKey(word) 函数没有新的最终 else 语句)在始终为 true if 语句内，当它必须返回 false 才能发生这种情况时，为什么其他类似的单词没有相同的采取的类(class)？ 不管怎样，它运行良好，我将把它留给专家来弄清楚为什么它会做上一个声明中所做的事情。

关于C 枚举不返回未指定的值，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42754832/

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