c_ch01_ex23.c

/*Exercise 1-23. Write a program to remove all comments from a C program. Don't forget to handle quoted strings and character constants properly. C comments don't nest.*/
#include <stdio.h>
#define UnComment	0
#define StarAfterSlash	1
#define StarAfterStar	2
#define SlashAfterStar	3
#define DoubleSlash	4
#define MAX		1000
void removeComment(char *str, int len);
int main()
{
        int len;
        char str[MAX];
        removeComment(str, MAX);
                printf("%s", str);
        return 0;
}
void removeComment(char *str, int len) {
        int c, i, state;
        i = state = UnComment;
        while ((c = getchar()) != EOF && i < len - 1) {
                switch (c) {
                        case '/':       if (state == UnComment)
                                                state = StarAfterSlash;
                                        else if (state == StarAfterSlash)
                                                state = DoubleSlash;
                                        else if (state == SlashAfterStar)
                                                state = UnComment;
                                        else if (state == DoubleSlash)
                                                str[i++] = ' ';
                                        else
                                                str[i++] = c;
                        break;
                        case '*':       if (state == StarAfterSlash)
                                                state = StarAfterStar;
                                        else if (state == StarAfterStar)
                                                state = SlashAfterStar;
                                        else if (state == DoubleSlash)
                                                str[i++] = ' ';
                                        else
                                                str[i++] = c;
                        break;
                        case '\n':      if (state == 1) {
                                                state = UnComment;
                                                str[i++] = '/';
                                                str[i++] = c;
                                        } else if (state == DoubleSlash) {
                                                state = UnComment;
                                                str[i++] = c;
                                        } else
                                                str[i++] = c;
			break;
                        default:        if (state == StarAfterSlash) {
                                                state = UnComment;
                                                str[i++] = '/';
                                                str[i++] = c;
                                        }
                                        else if (state == StarAfterStar || state == SlashAfterStar || state == DoubleSlash)
                                                str[i++] = ' ';
                                        else
                                                str[i++] = c;
                }
        }
        str[i] = '\0';
}