c - 如果单词出现在单词数组中，则排除该单词

Question

考虑到这段计算所有出现次数的代码，您如何删除常用词？

For example, if the word is from the top 100 English words then, don't count that word.

如果您根据维基百科取最常见的 100 个单词，您如何将它们添加到数组中并检查以不将它们计算在列表中: https://en.wikipedia.org/wiki/Most_common_words_in_English

数组形式的前 100 个最常见的单词:

#define NUMBER_OF_STRING 100
#define MAX_STRING_SIZE   50

char commonWords[NUMBER_OF_STRING][MAX_STRING_SIZE] = {"the", "be", "to", "of", "and", "a", "in", "that", "have", "I", "it", "for", "not", "on", "with", "he", "as", "you", "do", "at", "this", "but", "his", "by", "from", "they", "we", "say", "her", "she", "or", "an", "will", "my", "one", "all", "would", "there", "their", "what", "so", "up", "out", "if", "about", "who", "get", "which", "go", "me", "when", "make", "can", "like", "time", "no", "just", "him", "know", "take", "people", "into", "year", "your", "good", "some", "could", "them", "see", "other", "than", "then", "now", "look", "only", "come", "its", "over", "think", "also", "back", "after", "use", "two", "how", "our", "work", "first", "well", "way", "even", "new", "want", "because", "any", "these", "give", "day", "most", "us"};

代码示例:

/**
 * C program to count occurrences of all words in a file.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>

#define MAX_WORD  20000     /* max word size */
#define MAX_WORDS     8     /* initial number of struct to allocate */

#ifndef PATH_MAX
#define PATH_MAX   2048     /* max path (defined for Linux in limits.h) */
#endif

typedef struct {            /* use a struct to hold */
    char word[MAX_WORD];    /* lowercase word, and */
    int cap, count;         /* if it appeast capitalized, and its count */
} words_t;

char *strlwr (char *str)    /* no need for unsigned char */
{
    char *p = str;

    while (*p) {
        *p = tolower(*p);
        p++;
    }

    return str;
}

int main (void) {

    FILE *fptr;
    char path[PATH_MAX], word[MAX_WORD];
    size_t i, len, index = 0, max_words = MAX_WORDS;

    /* pointer to allocated block of max_words struct initialized zero */
    words_t *words = calloc (max_words, sizeof *words);
    if (!words) {   /* valdiate every allocation */
        perror ("calloc-words");
        exit (EXIT_FAILURE);
    }

    /* Input file path */
    printf ("Enter file path: ");
    if (scanf ("%s", path) != 1) {  /* validate every input */
        fputs ("error: invalid file path or cancellation.\n", stderr);
        return 1;
    }

    fptr = fopen (path, "r");   /* open file */
    if (fptr == NULL) {         /* validate file open */
        fputs ( "Unable to open file.\n"
                "Please check you have read privileges.\n", stderr);
        exit (EXIT_FAILURE);
    }

    while (fscanf (fptr, "%s", word) == 1) {  /* while valid word read */
        int iscap = 0, isunique = 1;    /* is captial, is unique flags */

        if (isupper (*word))            /* is the word uppercase */
            iscap = 1;

        /* remove all trailing punctuation characters */
        len = strlen (word);                    /* get length */
        while (len && ispunct(word[len - 1]))   /* only if len > 0 */
            word[--len] = 0;

        strlwr (word);                  /* convert word to lowercase */

        /* check if word exits in list of all distinct words */
        for (i = 0; i < index; i++) {
            if (strcmp(words[i].word, word) == 0) {
                isunique = 0;               /* set unique flag zero */
                if (iscap)                  /* if capital flag set */
                    words[i].cap = iscap;   /* set capital flag in struct */
                words[i].count++;           /* increment word count */
                break;                      /* bail - done */
            }
        }
        if (isunique) { /* if unique, add to array, increment index */
            if (index == max_words) {       /* is realloc needed? */
                /* always use a temporary pointer with realloc */
                void *tmp = realloc (words, 2 * max_words * sizeof *words);
                if (!tmp) { /* validate every allocation */
                    perror ("realloc-words");
                    break;  /* don't exit, original data still valid */
                }
                words = tmp;    /* assign reallocated block to words */
                /* (optional) set all new memory to zero */
                memset (words + max_words, 0, max_words * sizeof *words);
                max_words *= 2; /* update max_words to reflect new limit */
            }
            memcpy (words[index].word, word, len + 1);  /* have len */
            if (iscap)                      /* if cap flag set */
                words[index].cap = iscap;   /* set capital flag in struct */
            words[index++].count++;         /* increment count & index */
        }
    }
    fclose (fptr);  /* close file */

    /*
     * Print occurrences of all words in file.
     */
    puts ("\nOccurrences of all distinct words with Cap in file:");
    for (i = 0; i < index; i++) {
        if (words[i].cap) {
            strcpy (word, words[i].word);
            *word = toupper (*word);
            /*
             * %-15s prints string in 15 character width.
             * - is used to print string left align inside
             * 15 character width space.
             */
            printf("%-8d %s\n", words[i].count, word);
        }
    }
    free (words);

    return 0;
}

要测试的文本文件:(cars.txt)

A car (or automobile) is a wheeled motor vehicle used for transportation. Most definitions of car say they run primarily on roads, seat one to eight people, have four tires, and mainly transport people rather than goods.[2][3]

Cars came into global use during the 20th century, and developed economies depend on them. The year 1886 is regarded as the birth year of the modern car when German inventor Karl Benz patented his Benz Patent-Motorwagen. Cars became widely available in the early 20th century. One of the first cars accessible to the masses was the 1908 Model T, an American car manufactured by the Ford Motor Company. Cars were rapidly adopted in the US, where they replaced animal-drawn carriages and carts, but took much longer to be accepted in Western Europe and other parts of the world.

Cars have controls for driving, parking, passenger comfort, and a variety of lights. Over the decades, additional features and controls have been added to vehicles, making them progressively more complex. These include rear reversing cameras, air conditioning, navigation systems, and in-car entertainment. Most cars in use in the 2010s are propelled by an internal combustion engine, fueled by the combustion of fossil fuels. Electric cars, which were invented early in the history of the car, began to become commercially available in 2008.

There are costs and benefits to car use. The costs include acquiring the vehicle, interest payments (if the car is financed), repairs and maintenance, fuel, depreciation, driving time, parking fees, taxes, and insurance.[4] The costs to society include maintaining roads, land use, road congestion, air pollution, public health, health care, and disposing of the vehicle at the end of its life. Road traffic accidents are the largest cause of injury-related deaths worldwide.[5]

The benefits include on-demand transportation, mobility, independence, and convenience.[6] The societal benefits include economic benefits, such as job and wealth creation from the automotive industry, transportation provision, societal well-being from leisure and travel opportunities, and revenue generation from the taxes. People's ability to move flexibly from place to place has far-reaching implications for the nature of societies.[7] There are around 1 billion cars in use worldwide. The numbers are increasing rapidly, especially in China, India and other newly industrialized countries.[8]

当前输出:

Occurrences of all distinct words with Cap in file:
3        A
2        Motor
2        Most
2        One
8        Cars
29       The
1        German
1        Karl
2        Benz
1        Patent-motorwagen
1        Model
1        T
1        American
1        Ford
1        Company
1        Us
1        Western
1        Europe
1        Over
1        These
1        Electric
2        There
2        Road
1        People's
1        China
1        India

预期输出:(仅示例)

2        Motor
1        German
1        Karl
2        Benz
1        Patent-motorwagen
1        Model
1        T
1        American
1        Ford
1        Company

编辑更新:可能的解决方案:

同时继续(不起作用)

// skip the word if it is a common word
for (int i = 0; i < NUMBER_OF_STRING; i++) {
    if (strcmp(word, commonWords[i])==0) {
        continue;
    }
}

Answer 1

一种稍微更有效的方法是使用对 strstr 的单个调用，而不是尝试与前 100 个最常见的单词中的每一个进行比较。由于您知道 100 个最常见的单词，并且它们不会改变，因此您可以轻松确定最长的是 7 个字符。换句话说，您只需要测试 word 是否是最常见的词之一，如果它小于:

#define TOP_LEN       8     /* longest string in TOP100 + nul-character */

由于单词没有改变，您可以继续:

const char TOP100[] = " the be to of and a in that have i it for not on with"
                " he as you do at this but his by from they we say her she or"
                " an will my one all would there their what so up out if about"
                " who get which go me when make can like time no just him know"
                " take people into year your good some could them see other"
                " than then now look only come its over think also back after"
                " use two how our work first well way even new want because"
                " any these give day most us ";

(注意每个单词之前的空格和之后的空格，这允许您创建一个teststr通过在单词的两边包含一个空格来使用 strstr 进行搜索。'I' 已转换为小写以在 strlwr (word) 之后工作； )

(另请注意:您还可以在 #define TOP100 "the ... us " 中使用常量文字，但它会换行并可怕地滚动到页面之外在这里——由你决定)

有了 100 个最常用单词的常量字符串，唯一需要添加的是:

        ...
        strlwr (word);                  /* convert word to lowercase */

        /* check against 100 most common words (TOP100) */
        if (len < TOP_LEN) {                    /* word less than TOP_LEN? */
            char teststr[TOP_LEN * 2];          /* buffer for " word " */
            sprintf (teststr, " %s ", word);    /* create teststr */
            if (strstr (TOP100, teststr))       /* check if in TOP100 */
                continue;                       /* if so, get next word */
        }
        ...

如上所示，您检查单词是否为 7 个字符或更少(否则无需检查最常见的字符)。然后你声明一个 teststr 来保存你的字符串，两端都有一个空格。 (因为最长的常用词是 7 个字符，那么 7 个字符加上 2 个空格是 9 个字符，再加上 nul 字符是 10 个字符，所以 16 个字符在这里绰绰有余。)

只需调用 sprintf 即可将空格放在 word 的每一端，然后调用 strstr 是查看 word 是否在前 100 个最常见单词中所需的全部内容。如果是，则无需继续，只需继续并获取下一个单词即可。

将其完全放入您的代码中您将拥有:

/**
 * C program to count occurrences of all words in a file.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>

#define MAX_WORD  20000     /* max word size */
#define MAX_WORDS     8     /* initial number of struct to allocate */
#define TOP_LEN       8     /* longest string in TOP100 */

#ifndef PATH_MAX
#define PATH_MAX   2048     /* max path (defined for Linux in limits.h) */
#endif

const char TOP100[] = " the be to of and a in that have i it for not on with"
                " he as you do at this but his by from they we say her she or"
                " an will my one all would there their what so up out if about"
                " who get which go me when make can like time no just him know"
                " take people into year your good some could them see other"
                " than then now look only come its over think also back after"
                " use two how our work first well way even new want because"
                " any these give day most us ";

typedef struct {            /* use a struct to hold */
    char word[MAX_WORD];    /* lowercase word, and */
    int cap, count;         /* if it appeast capitalized, and its count */
} words_t;

char *strlwr (char *str)    /* no need for unsigned char */
{
    char *p = str;

    while (*p) {
        *p = tolower(*p);
        p++;
    }

    return str;
}

int main (void) {

    FILE *fptr;
    char path[PATH_MAX], word[MAX_WORD];
    size_t i, len, index = 0, max_words = MAX_WORDS;

    /* pointer to allocated block of max_words struct initialized zero */
    words_t *words = calloc (max_words, sizeof *words);
    if (!words) {   /* valdiate every allocation */
        perror ("calloc-words");
        exit (EXIT_FAILURE);
    }

    /* Input file path */
    printf ("Enter file path: ");
    if (scanf ("%s", path) != 1) {  /* validate every input */
        fputs ("error: invalid file path or cancellation.\n", stderr);
        return 1;
    }

    fptr = fopen (path, "r");   /* open file */
    if (fptr == NULL) {         /* validate file open */
        fputs ( "Unable to open file.\n"
                "Please check you have read privileges.\n", stderr);
        exit (EXIT_FAILURE);
    }

    while (fscanf (fptr, "%s", word) == 1) {  /* while valid word read */
        int iscap = 0, isunique = 1;    /* is captial, is unique flags */

        if (isupper (*word))            /* is the word uppercase */
            iscap = 1;

        /* remove all trailing punctuation characters */
        len = strlen (word);                    /* get length */
        while (len && ispunct(word[len - 1]))   /* only if len > 0 */
            word[--len] = 0;

        strlwr (word);                  /* convert word to lowercase */

        /* check against 100 most common words (TOP100) */
        if (len < TOP_LEN) {                    /* word less than TOP_LEN? */
            char teststr[TOP_LEN * 2];          /* buffer for " word " */
            sprintf (teststr, " %s ", word);    /* create teststr */
            if (strstr (TOP100, teststr))       /* check if in TOP100 */
                continue;                       /* if so, get next word */
        }

        /* check if word exits in list of all distinct words */
        for (i = 0; i < index; i++) {
            if (strcmp(words[i].word, word) == 0) {
                isunique = 0;               /* set unique flag zero */
                if (iscap)                  /* if capital flag set */
                    words[i].cap = iscap;   /* set capital flag in struct */
                words[i].count++;           /* increment word count */
                break;                      /* bail - done */
            }
        }
        if (isunique) { /* if unique, add to array, increment index */
            if (index == max_words) {       /* is realloc needed? */
                /* always use a temporary pointer with realloc */
                void *tmp = realloc (words, 2 * max_words * sizeof *words);
                if (!tmp) { /* validate every allocation */
                    perror ("realloc-words");
                    break;  /* don't exit, original data still valid */
                }
                words = tmp;    /* assign reallocated block to words */
                /* (optional) set all new memory to zero */
                memset (words + max_words, 0, max_words * sizeof *words);
                max_words *= 2; /* update max_words to reflect new limit */
            }
            memcpy (words[index].word, word, len + 1);  /* have len */
            if (iscap)                      /* if cap flag set */
                words[index].cap = iscap;   /* set capital flag in struct */
            words[index++].count++;         /* increment count & index */
        }
    }
    fclose (fptr);  /* close file */

    /*
     * Print occurrences of all words in file.
     */
    puts ("\nOccurrences of all distinct words with Cap in file:");
    for (i = 0; i < index; i++) {
        if (words[i].cap) {
            strcpy (word, words[i].word);
            *word = toupper (*word);
            /*
             * %-15s prints string in 15 character width.
             * - is used to print string left align inside
             * 15 character width space.
             */
            printf("%-8d %s\n", words[i].count, word);
        }
    }
    free (words);

    return 0;
}

示例使用/输出

与上次一样，您的预期输出:(仅示例) 是错误的，因为您的代码中没有任何内容可以删除复数、所有 或复数所有格，因此您的 cars.txt 文件的输出将是:

$ ./bin/unique_words_exclude_top_100
Enter file path: dat/cars.txt

Occurrences of all distinct words with Cap in file:
2        Motor
8        Cars
1        German
1        Karl
2        Benz
1        Patent-motorwagen
1        Model
1        T
1        American
1        Ford
1        Company
1        Western
1        Europe
1        Electric
2        Road
1        People's
1        China
1        India

检查一下，如果您还有其他问题，请告诉我。