c - 如何在c语言的文本输入文件中找到匹配括号或大括号的位置？

Question

我正在用 C 编写一个程序..该程序打开一个包含类似 C 源代码的纯文本文件，读取它，并输出一个与第一个内容相同的文件，但所有注释都被删除。该程序必须检查所有括号是否匹配，如果不匹配，程序应该显示一条错误消息，显示错误类型和遇到此错误的行号。(我显示了一条错误消息，但如何找到错误位置。 .?) 输入和输出文件被传递给程序a####nd行参数，如下所示: ./your_executable 输入文件.txt 输出文件.txt

这是我编写的代码:

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

/* Functions */
void check_comment (char) ;  // checks for both types of comments, then passes on control to below comments
void block_comment () ;   //  handles block or multiline comments
void single_comment () ;   // handles single line comments

/* 2 file pointers - 1st is for the file in which we check for comments,
and 2nd is the file in which we copy the code after removing comments  */
FILE *fp , *fp2;

int main(void)
{
    char c;

    fp = fopen ("inputfile.txt","r") ;   // open the first file in read mode
    fp2 = fopen ("outputfile.txt","w") ;    // open the second file in write mode
    while((c=fgetc(fp))!=EOF)       // read the file character by character
        check_comment(c);   // check for each character if it seems like the beginning of a comment

     //  close both the files at the end of the program
    fclose(fp);
    fclose(fp2);

    FILE *fp;
    char fname[20];
    char brackets[20] = "{}[]()";
    int bracketCounts[6] = {0};
    char * found;
    int i;

    printf("Please enter the destination of the file: \n");
    scanf("%s", fname);

    if ((fp = fopen(fname, "r")) == NULL){
        printf("Problem opening file!\n");
        return 0x00;
    }

    printf("File opened correctly\n");

    // counting various parentheses
    while ((c = getc(fp)) != EOF){
        found = strchr(brackets, c);
        if (found != NULL) {
            bracketCounts[found - brackets]++;
        }
    }

    // dont't forget to close file after reading is done
    fclose(fp);

    // checking parentheses counters
    for (i=0; i < 6; i+=2) {
        if (bracketCounts[i] != bracketCounts[i+1]) {
            printf("Unbalanced parentheses !\n");
            return 0x00;
        }
    }

    printf("All parentheses are OK!\n");

    return 0;
}

// function that handles both types of comments
void check_comment(char c)
{
    char d;

    if( c == '/')   // if the character starts with '/', it 'could' be a comment
    {
        if((d=fgetc(fp))=='*')   // if the next character we read is '*', it is the beginning of multiblock comment
            block_comment();  // pass control to function that handles multiblock comments

        else if( d == '/')   // else if the next character we read is '/', it is the beginning of single line comment
        {
            single_comment();// pass control to function that handles single line comment

        }
        else
        {
            // if both the cases fail, it is not a comment, so we add the character as it is in the new file.
            fputc(c,fp2);
            fputc(d,fp2);
        }
    }

    // again, if all above fails, we add the character as it is in the new file.
    else
        fputc(c,fp2);
}


// function that handles block comments
void block_comment()
{

 char d,e;

    while((d=fgetc(fp))!=EOF)   // the block comment has started, read the character by character
    {
    /* keep reading the characters and do nothing,
    as they do not have to be copied into the new file (we are removing the comments)
    */
        if(d=='*')    // if the comment 'seems' like ending
        {
            e=fgetc(fp);  // check if it actually ends (block comments end with '*/')

            if(e=='/')  // if the comment 'has' ended, return from the function
                return;
        }
   }

}

// function that handles single line comments
void single_comment()
{
 char d,e;

    while((d=fgetc(fp))!=EOF)  // the single line comment has started, read the character by character
    {
    /* keep reading the characters and do nothing,
    as they do not have to be copied into the new file (we are removing the comments)
    */
        if(d=='\n')   // check if the comment ends (single comments end with '\n', or newline)
            return;  // if the comment 'has' ended, return from the function

    }

}

Answer 1

您可以在读取输入文件时实现或使用堆栈数据结构，如果您得到 { , ( 或 [ 压入堆栈，如果您得到 }, ) 或 ] 弹出堆栈，输入文件堆栈末尾应该为空，然后您将获得正确的匹配，否则会发生一些不匹配。

与括号一起，您可以保留行号(或位置等)

例如:1 ( 2(某事) 3 东西)，

push (, line1，然后push (, line2，当你得到 ) pop (, line2 依此类推，在这种情况下，如果您没有得到第二个结束 )，您可以说 (, line1 缺少关闭。