c - 了解用于检测 C 风格注释的状态机

Question

除了处理嵌套评论输入的方式外，我已经了解该程序的全部功能。我不清楚 State Star 的功能。 c!='*' 意味着什么？

假设输入是haha/* hello/*world */，那么在第一个星号之后，如果出现斜线，控制就转移到PROGRAM状态。但是，为什么要考虑 c!='*'？

#include<stdio.h>
#include<conio.h>

void main()
{
enum{ /*Enum construct declares states */
    PROGRAM,
    SLASH,
    STAR,
    QUOTE,
    COMMENT,
    LITERAL
}state;

/* If state is quote then its either " or '*/

state = PROGRAM;

for(;;)
{
    int c = getchar();
    int quote = 0 ;

    switch(state) {
    case SLASH:
        /* Program text following a slash */
        if (c == '*') {
            state = COMMENT;
            break;
        }
        putchar('/');
        state = PROGRAM;

    case PROGRAM:
        /*Program Text*/
        if (c == '\''||c == '"') {
            state = QUOTE;
            quote = c;
            putchar(quote);
        }
        else if (c == '/')
            state = SLASH;
        else
            putchar(c);
        break;

    case COMMENT:
        /* Comment */
        if (c == '*')
            state = STAR;
        break;

    case STAR:
        /*Comment following a Star */
        if (c == '/')
            state = PROGRAM;
        else if (c != '*') {
            state = COMMENT;
            putchar(' ');
        }
        break;

    case QUOTE:
        /*Within a quote or a string */
        putchar(c);
        if (c == '\\')
            state = LITERAL;
        else if (c == quote)
            state = PROGRAM;
        break;

    case LITERAL:
        /*Within a literal having /*/
        putchar(c);
        state = QUOTE;
        break;
    }
}

printf("Can it handle this /* I wonder */");
getch();
}

Answer 1

这是为了处理这样的输入:

blah /* comment **/ blah
                 ^

如果您在我标记的位置恢复到 COMMENT，那么您将不会寻找 / 以恢复到 PROGRAM。您需要留在 STAR。