Question

我正在编写一个程序，它将文本文件作为输入，生成单词的索引并在文件和屏幕中输出输出（索引）。我编码如下，试图发现问题或者至少缩小它，但我不能。如果有人可以帮助或发现语法或代码逻辑方面的问题，我会很高兴知道。

void main(int argc, char * argv[])
{   
    //clearscreen
    clrscr();

//if arguments are less that default of the program
if (argc < 2) 
{
    cout << "You should've input 3 arguments." ;
    return;
}

//opening the input file and defining a pointer which points to it as argv[1]
FILE *fPtr = fopen(argv[1], "r+");

//defining a 2D array to hold maximum to 200 words holding maximum to 20 characters
char words[200][20];

//initializing words 2D array with zero ASCII
for(int i = 0; i < 200; i++)
    for(int j = 0; j < 20; j++)
        words[i][j] = 255;

//defining an 2D whi array which is supposed to show how many times words are placed in which lines in a defined layout
//it holds maximum to 200 words holding maximum 100 sentences
int index[200][100];

//initializing the index 2D array with zero ASCII
for(i = 0; i < 200; i++)
    for(j = 0; j < 100; j++)
        index[i][j] = 0;

//this array of characters max to 2000 is supposed to hold each line which is gotten with fgets
char buff[2000];

//initializing the buff array with zero ASCII
for(i = 0; i < 2000; i++)
    buff[i] = 0;

//the max of the words used in the source file is 200. but this valuable named as 'last' says how many words are used in this source file
//its initalized as no words is held
int last = 0;

//defining a pointer to char of punctuation mark characters. all ASCII codes expect for a - z, A - Z, 0 - 9 and newline
char *punc;

//initializing punctuation marks array
for(i = 0; i < 256; i++)
{
    if(i == 10)
        continue;
    if(i >= '0' && i <= '9')
        continue;
    if(i >= 'a' && i <= 'z')
        continue;
    if(i >= 'A' && i <= 'Z')
        continue;
    char *string = (char *) &i;
    strncat(punc, string, 1);
}

//how many lines is read from the source file
int lineread = 0;

//a word which the processes are done on that
char *word;

//one line read
while( fgets(buff, 1999, fPtr) != NULL)
{
    //how many words is read from the source file in the current line
    int wordread = 0;

    word = strtok(buff, punc);

    //one word read
    while( word != NULL)
    {
        //sorting
        int k = 0;
        while(strcmp(word, words[k])> 0)
            k++;
        if(strcmp(word, words[k]))
        {

            for(int l = last; l >= 0; l--)
            {
                strcpy(words[l + 1],words[l]);
                for(int o = 0; o <= lineread; o++)
                    index[l + 1][o] = index[l][o];
            }
            last++;
            strcpy(words[k],word);
            for(l = 0; l <= lineread; l++)
                index[k][l] = 0;
        }
        index[k][lineread]++;
        wordread++;//go to next word
        word = strtok(NULL, punc);
    }
    lineread++;//go to next line
}
//closing the input file
fclose(fPtr);

//opening the output file and defining a pointer which points to it as argv[2]
FILE *fPtr2 = fopen(argv[2], "w+");

//showing the index in cmd
for(i = 0; i <= last; i++)
{   
    printf("%-20s" , words[i]);
    fprinf(fPtr2, "%-20s" , words[i]);
    int m = 0;
    for(j = 0; j <= lineread; j++)
    {
        if(m)
        {
            printf("%c", ',');
            fprintf(fPtr2, "%c", ',');
        }
        if(index[i][j])
        {
            printf("%i", j + 1);
            fprintf(fPtr2, "%i" ,j + 1);
        }
        if(index[i][j] > 1)
        {       
            printf("(%i)", index[i][j]);
            fprintf(fPtr2, "(%i)", index[i][j]);
                m = 1;
        }
    }
    printf("\n");
    fprintf(fPtr2, "\n");
}

//closing the output file
fclose(fPtr);
}

现在它出错，因为异常程序终止NULL指针赋值。我必须使用turbo c，我使用DOS SHELL。资源中有一个文件名为“input.txt”。在DOS SHELL我写这个：

programname.exe input.txt output.txt

如果input.txt是这样的话，

和我想要的输出：

hello. hello.
how are
you? hello.

desired output:

hello                   1(2),3           //2 times in line 2, 1 time in line 1
how                     2                //1 time in line 2
are                     2               //1 time in line 2
you                     3               //1 time in line 3

Answer 1

问题在于这一行：

while(strcmp(word, words[k])> 0)

因为index被初始化为255并且根据算法strcmp的工作基于，对于第一个单词，代码正常工作并将其放入word[0]但是对于第二个词它将无法正常工作。例如：

first word: Kittens
second word: Biscuits

首先strcmp将Kittens与255 ASCII code进行比较。结果是Kitten更小，并且流程会将其放在word[0]中。但是对于第二个单词，strcmp将Biscuits与Kittens进行比较，结果是Kittens更大，程序将通过另一个word[]块不想要。该程序将通过将word[]初始化为0并使用此代码而非首次提及的代码来修复：

while(strcmp(word, words[k])> 0)

为什么我的程序“创建索引”不起作用？

1 个答案: