C - 查找单词并获取下一个

Question

我正在逐行解析C文件。这里是什么，我试图做一个为例：

我有例如线： word word word WORDTOFIND: word1 word2 word word

我想要做的是：当我发现这个词WORDTOFIND，得到两个接下来的话（word1在这种情况下为word2）。在C中有一种简单的方法吗？我知道strstr功能，但我找不到一个方法来得到接下来的两个词word1和word2后，我找到了一个好的。

Answer 1

一种方法是这样的：

int main(void) 
{ 
    char *str = "rated rat cat bat hat"; 
    char *key = "rat "; 
    char *pointer = NULL; 
    char nwords = 2; 

    if ((pointer = strstr(str, key)) != NULL) 
    { 
     while (*pointer != ' ') pointer++; 
     while (nwords >= 0) 
     { 
      printf("%c", *pointer); 
      if (*pointer == ' ') { 
       nwords--; 
      } else if (*pointer == '\0') { 
       exit(0); 
      } 

      pointer++; 
     } 
    } 
} 

Answer 2

你可以尝试这样的形式给出，使用strtok解析在每一个空间的话。此代码还使用malloc和realloc为字符串数组分配空间，并在需要时增大该空间。

的代码看起来是这样的：

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

#define MAXCHAR 100 

void exit_if_null(void *ptr, const char *msg); 
char *stripped_word(char *word); 

int 
main(int argc, char const *argv[]) { 
    FILE *filename; 
    char line[MAXCHAR]; 
    char *word, *newword; 
    char **allwords; 
    int init_size = 8, count = 0, i; 
    const char *key = "WORDTOFIND"; 

    filename = fopen("files.txt", "r"); 

    if (filename == NULL) { 
     fprintf(stderr, "%s\n", "Error reading file!"); 
     exit(EXIT_FAILURE); 
    } 

    allwords = malloc(init_size * sizeof(*allwords)); 
    exit_if_null(allwords, "Initial Allocation"); 

    while (fgets(line, MAXCHAR, filename) != NULL) { 
     word = strtok(line, " \n"); 

     while (word != NULL) { 
      if (count == init_size) { 
       init_size *= 2; 
       allwords = realloc(allwords, init_size * sizeof(*allwords)); 
      } 

      allwords[count] = malloc(strlen(word)+1); 
      exit_if_null(allwords[count], "Initial Allocation"); 

      newword = stripped_word(word); 

      strcpy(allwords[count], newword); 

      count++; 

      word = strtok(NULL, " \n"); 

      free(newword); 
     } 
    } 

    for (i = 0; i < count; i++) { 
     if (strcmp(key, allwords[i]) == 0) { 
      printf("Next two words:\n"); 
      printf("%s\n", allwords[i+1]); 
      printf("%s\n", allwords[i+2]); 
     } 
     free(allwords[i]); 
     allwords[i] = NULL; 
    } 

    free(allwords); 
    allwords = NULL; 

    return 0; 
} 

void 
exit_if_null(void *ptr, const char *msg) { 
    if (!ptr) { 
     printf("Unexpected null pointer: %s\n", msg); 
     exit(EXIT_FAILURE); 
    } 
} 

char 
*stripped_word(char *word) { 
    int i, pos = 0; 
    char *result; 

    result = malloc(strlen(word)+1); 
    exit_if_null(result, "Initial Allocation"); 

    for (i = 0; word[i] != '\0'; i++) { 
     if (isalpha(word[i]) || isdigit(word[i])) { 
      result[pos++] = word[i]; 
     } 
    } 

    result[pos] = '\0'; 

    return result; 
}