删除 C 程序中的所有注释 - 对此代码有任何可能的改进吗?

2024-01-24

我正在从 K&R 书中学习 C,对于第一章中的练习 1.23,我必须编写一个程序,根据用户输入的一些 C 代码删除所有注释。这是我迄今为止完成的程序。我可以对其进行任何改进吗?

/**
 Tuesday, 10/07/2013

 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 MAX_LENGTH 65536
#define NOT_IN_COMMENT 0
#define SINGLE_COMMENT 1
#define MULTI_COMMENT  2

main()
{
    char code[MAX_LENGTH];        /* Buffer that stores the inputted code */
    int size = 0;                 /* Length of the inputted code */
    int loop;                     /* Integer used for the for loop */
    char c;                       /* Character to input into */
    int status = NOT_IN_COMMENT;  /* Are we in a comment? What type? */
    int in_string = 0;            /* Are we inside of a string constant? */
    char last_character;          /* Value of the last character */


    /* Input all code into the buffer until escape sequence pressed */
    while ((c = getchar()) != EOF)
        code[size++] = c; 
    code[size] = '\0'; 


    /* Remove all comments from the code and display results to user */
    for (loop = 0; loop < size; loop++) {
        char current = code[loop]; 

        if (in_string) {
            if (current == '"') in_string = 0; 
            putchar(current);
        }

        else {
            if (status == NOT_IN_COMMENT) {
                if (current == '"') {
                    putchar(current);
                    in_string = 1; 
                    continue; 
                }

                if (current == '/' && last_character == '/') status = SINGLE_COMMENT;
                else if (current == '*' && last_character == '/') status = MULTI_COMMENT; 
                else if (current != '/' || (current == '/' && loop < size-1 && !(code[loop+1] == '/' || code[loop+1] == '*'))) putchar(current); 
            }

            else if (status == SINGLE_COMMENT) {
                if (current == '\n') {
                    status = NOT_IN_COMMENT; 
                    putchar('\n');
                }
            }

            else if (status == MULTI_COMMENT) {
                if (current == '/' && last_character == '*') status = NOT_IN_COMMENT; 
            }
        }

        last_character = current; 
    }
}

将注释剥离移到一个函数中(更有用),并使用 fgets() 一次读取一行,last_character 不明确(它意味着最后一个还是前一个?),这使用了更少的 putchar() 调用,仅每行一个 printf (可以使用 put),保留您正在做的大部分事情,

#include <stdio.h>
#include <string.h>
#define MAX_LENGTH 65536

#define NOT_IN_COMMENT 0
#define SINGLE_COMMENT 1
#define MULTI_COMMENT  2
int status = NOT_IN_COMMENT;  /* Are we in a comment? What type? */
int in_string = 0;            /* Are we inside of a string constant? */
char* stripcomments(char* stripped,char* code)
{
    int ndx;                      /* index for code[] */
    int ondx;                     /* index for output[] */
    char prevch;                  /* Value of the previous character */
    char ch;                      /* Character to input into */

    /* Remove all comments from the code and display results to user */
    for (ndx=ondx=0; ndx < strlen(code); ndx++)
    {
        char current = code[ndx];

        if (in_string) {
            if (current == '"') in_string = 0;
            stripped[ondx++] = current;
        }
        else {
            if (status == NOT_IN_COMMENT) {
                if (current == '"') {
                    stripped[ondx++] = current;
                    in_string = 1;
                    continue;
                }

                if (current == '/' && prevch == '/') status = SINGLE_COMMENT;
                else if (current == '*' && prevch == '/') status = MULTI_COMMENT;
                else if (current != '/' || (current == '/' && ndx < strlen(code)-1 && !(code[ndx+1] == '/' || code[ndx+1] == '*'))) stripped[ondx++] = current;
            }

            else if (status == SINGLE_COMMENT) {
                if (current == '\n') {
                    status = NOT_IN_COMMENT;
                    stripped[ondx++] = '\n';
                }
            }

            else if (status == MULTI_COMMENT) {
                if (current == '/' && prevch == '*') status = NOT_IN_COMMENT;
            }
        }
        prevch = current;
    }
    stripped[ondx] = '\0';
    return(stripped);
}

int main(void)
{
    char code[MAX_LENGTH];        /* Buffer that stores the inputted code */
    char stripped[MAX_LENGTH];

    while( fgets(code,sizeof(code),stdin) )
    {
        //printf("%s\n",code);
        //strip comments...
        stripcomments(stripped,code);
        if( strlen(stripped) > 0 ) printf("%s",stripped);
    }
}

我将让您删除多余的空白行。

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