C语言实现英文文章单词拼写检查

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

#define MAX_WORD_LEN 50
#define MAX_WORDS_NUM 1000

// 读取单词索引表，返回单词个数
int readIndex(char indexFile[], char indexTable[][MAX_WORD_LEN+1]) {
    FILE *fp;
    int num = 0;
    char word[MAX_WORD_LEN+1];

    fp = fopen(indexFile, 'r');
    if (fp == NULL) {
        printf('Error: cannot open file %s\n', indexFile);
        exit(1);
    }

    while (fgets(word, MAX_WORD_LEN+1, fp) != NULL) {
        word[strcspn(word, '\r\n')] = '\0'; // 去掉行末的换行符
        strcpy(indexTable[num], word);
        num++;
    }

    fclose(fp);
    return num;
}

// 判断一个字符是否为字母
int isLetter(char c) {
    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}

// 将一个字符串转换为小写
void toLower(char str[]) {
    int i;
    for (i = 0; str[i] != '\0'; i++) {
        str[i] = tolower(str[i]);
    }
}

// 读取英文文章，返回单词个数
int readArticle(char articleFile[], char article[][MAX_WORD_LEN+1]) {
    FILE *fp;
    int num = 0;
    char c, word[MAX_WORD_LEN+1];
    int i, j, len;

    fp = fopen(articleFile, 'r');
    if (fp == NULL) {
        printf('Error: cannot open file %s\n', articleFile);
        exit(1);
    }

    i = 0;
    while ((c = fgetc(fp)) != EOF) {
        if (isLetter(c)) {
            word[i] = c;
            i++;
        } else if (i > 0) {
            word[i] = '\0';
            toLower(word);
            strcpy(article[num], word);
            num++;
            i = 0;
        }
    }

    if (i > 0) { // 处理最后一个单词
        word[i] = '\0';
        toLower(word);
        strcpy(article[num], word);
        num++;
    }

    fclose(fp);
    return num;
}

// 比较两个字符串的大小，返回值为0表示相等，小于0表示s1<s2，大于0表示s1>s2
int cmpString(const void *s1, const void *s2) {
    return strcmp(*(const char **)s1, *(const char **)s2);
}

// 查找单词在单词索引表中的位置，返回值为-1表示未找到
int searchWord(char word[], char indexTable[][MAX_WORD_LEN+1], int num) {
    int left = 0, right = num - 1, mid;
    while (left <= right) {
        mid = (left + right) / 2;
        if (strcmp(word, indexTable[mid]) == 0) {
            return mid;
        } else if (strcmp(word, indexTable[mid]) < 0) {
            right = mid - 1;
        } else {
            left = mid + 1;
        }
    }
    return -1;
}

int main() {
    char indexFile[] = 'index.txt';
    char articleFile[] = 'in.txt';
    char errorFile[] = 'error.txt';
    char indexTable[MAX_WORDS_NUM][MAX_WORD_LEN+1];
    char article[MAX_WORDS_NUM][MAX_WORD_LEN+1];
    char errorWords[MAX_WORDS_NUM][MAX_WORD_LEN+1];
    int indexNum, articleNum, errorNum = 0;
    int i, pos;

    // 读取单词索引表
    indexNum = readIndex(indexFile, indexTable);

    // 读取英文文章
    articleNum = readArticle(articleFile, article);

    // 检查单词是否在单词索引表中出现
    for (i = 0; i < articleNum; i++) {
        pos = searchWord(article[i], indexTable, indexNum);
        if (pos == -1) {
            strcpy(errorWords[errorNum], article[i]);
            errorNum++;
        }
    }

    // 对错误单词按字典序排序
    qsort(errorWords, errorNum, sizeof(errorWords[0]), cmpString);

    // 输出错误单词到文件
    FILE *fp;
    fp = fopen(errorFile, 'w');
    if (fp == NULL) {
        printf('Error: cannot open file %s\n', errorFile);
        exit(1);
    }
    for (i = 0; i < errorNum; i++) {
        fprintf(fp, '%s\n', errorWords[i]);
    }
    fclose(fp);

    return 0;
}