如何在C中将一个字符变成一个单词

Question

我目前正在从一个文件中收集输入，但我的程序将每个字母而不是每个单词分隔到 char 数组中。如何更改我的代码以获取每个单词？

char c, fileName[20];
FILE *f;

void getFile() {    
    f = fopen(fileName, "r");

    while((c = fgetc(f)) != EOF) {
        printf("%c",c);
    }
    fclose(f);
}

Answer 1

改用fscanf(3)

char word[256], *p;
while(fscanf(f, "%s", &word) != EOF) {
     printf("%s\n", word);
     /* break down word into individual chars */
     for(p=word; *p; p++) {
         printf("%c ", *p);
         }
     printf("\n");
     }

Answer 2

你可以使用 char * fgets ( char * str, int num, FILE * stream ); 然后使用 char *strtok(char *str, const char *delim) 例如

#include <stdio.h>

 int main()
{
 FILE * pFile;
 char mystring [100];
 const char delimters[2] = " ,:";
 char *token;

 pFile = fopen ("myfile.txt" , "r");
 if (pFile == NULL) perror ("Error opening file");
 else {
   if ( fgets (mystring , 100 , pFile) != NULL )

    /* get the first token */
     token = strtok(mystring, delimiters);

  /* walk through other tokens */
  while( token != NULL ) 
 {
    printf( " %s\n", token );

  token = strtok(NULL, delimiters);
 }

   fclose (pFile);
  }
 return 0;
}

Answer 3

第一个问题 fgetc() return 是一个 int 您不能将 EOF 存储在 char 变量中。
您应该检查 fopen() 是否 return NULL。

你可以用这个技巧来读这样的字

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

#define MAX_BUFFER_SIZE 256

char **load_words_from_file(const char *filename)
{
    size_t wordcount;
    size_t charcount;
    char   buffer[MAX_BUFFER_SIZE];
    int    chr;
    FILE  *file;
    char **words;
    void  *pointer;

    file = fopen(filename, "r");
    if (file == NULL)
        return NULL;
    wordcount = 0;
    charcount = 0;
    words     = NULL;
    while ((chr = fgetc(file)) != EOF)
    {
        /* it's a white space or it exceeded buffer size, it's a word delimiter */
        if ((isspace(chr) != 0) || (charcount >= sizeof(buffer) - 1))
        {
            /* 'nul' terminate 'buffer' for strcpy() and strlen() */
            buffer[charcount] = '[=10=]';
            pointer           = realloc(words, (1 + wordcount) * sizeof(char *));
            if (pointer == NULL) /* failure, free allocated memory and return NULL */
                goto failure;
            words            = pointer;
            words[wordcount] = malloc(1 + charcount);
            charcount        = 0; /* reset character count */
            if (words[wordcount] == NULL)
                goto failure;
            strcpy(words[wordcount], buffer);

            wordcount += 1;
        }
        else
        {
            /* store the character and count it */
            buffer[charcount] = (char)chr;
            charcount        += 1;
        }
    }
    pointer = realloc(words, (1 + wordcount) * sizeof(char *));
    if (pointer == NULL)
        goto failure;
    words            = pointer;
    words[wordcount] = NULL; /* this will let you know when to stop fetching words */

    fclose(file);
    return words;
failure:
    for (size_t i = 0 ; i < wordcount ; ++i)
        free(words[i]);
    free(words);
    return NULL;
}

int
main()
{
    const char *filename = "your-file-name-here";
    char      **words    = load_words_from_file(filename);
    size_t      counter  = 0;

    if (words == NULL)
    {
        printf("no words found in the file\n");
        return -1;
    }
    while (words[counter] != NULL)
    {
        printf("%zuth word: %s\n", 1 + counter, words[counter]);
        free(words[counter]); /* this program will not use it again */
        counter += 1;
    }
    free(words);
    return 0;
}

strtok() 方法也可以，但更难理解。

注意goto的使用，这是一个良性的使用，虽然有些人认为goto总是有害的，但事实并非如此，这样使用它会使程序坚持DRY 原理.

Answer 4

您可以将扫描集与 fscanf 或 sscanf 一起使用。此扫描集 %29[a-zA-Z] 读取小写和大写英文字符，并在遇到不在集合中的字符时停止。 29 限制了要读取的最大字符数，以免覆盖缓冲区，word[30]。当 fscanf 失败时，else 将从文件中读取一个字符并让 fscanf 再次尝试读取另一个单词。
这个也是用命令行传入文件读取为argv[1].

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

int main( int argc, char *argv[])
{
    char word[30] = {'[=10=]'};
    int ch = 0;
    FILE *pf = NULL;

    if ( argc != 2) {//command requires program name and a file name
        printf ( "useage: program filename\n");
        return 1;
    }

    if ( ( pf = fopen ( argv[1], "r")) == NULL) {
        perror ( "could not open file");
        return 1;
    }

    while ( 1) {
        if ( ( fscanf ( pf, "%29[a-zA-Z]", word)) == 1) {
            printf ( "%s\n", word);
        }
        else {
            if ( ( ch = fgetc ( pf)) == EOF) {//read one character and check for end of file
                break;
            }
            //could do something here with the value of ch if needed
        }
    }
    printf ( "--DONE--\n");

    return 0;
}

这将为每个单词分配一个数组。添加单词时，使用 realloc 扩展数组。

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

int main( int argc, char *argv[])
{
    char **words = NULL;//pointer for words
    char **temp = NULL;
    char word[30] = {'[=11=]'};
    int ch = 0;
    int each = 0;
    int found = 0;
    int count = 0;
    int wordsize = 0;
    FILE *pf = NULL;

    if ( argc != 2) {//command requires program name and a file name
        printf ( "useage: program filename\n");
        return 1;
    }

    if ( ( pf = fopen ( argv[1], "r")) == NULL) {
        perror ( "could not open file");
        return 1;
    }

    while ( 1) {
        if ( ( fscanf ( pf, "%29[a-zA-Z]", word)) == 1) {
            found = 0;
            for ( each = 0; each < wordsize; each++) {
                if ( strcmp ( words[each], word) == 0) {
                    found = 1;
                    break;
                }
            }
            if ( found == 0) {
                wordsize += 1;// increment number of words
                temp = realloc ( words, wordsize * sizeof ( char *));//reallocate for another word
                if ( temp != NULL) {
                    words = temp;
                    words[wordsize - 1] = malloc ( strlen ( word) + 1);//malloc for the word itself
                    if ( words[wordsize - 1] != NULL) {
                        strcpy ( words[wordsize - 1], word);
                    }
                    else {
                        printf ( "malloc failed\n");
                        wordsize -= 1;
                        break;
                    }
                }
                else {
                    printf ( "realloc failed\n");
                    wordsize -= 1;
                    break;
                }
            }
            printf ( "%s\n", word);
        }
        else {
            if ( ( ch = fgetc ( pf)) == EOF) {//read one character and check for end of file
                break;
            }
            //something could be done with ch if needed
        }
    }
    printf ( "--DONE Reading file--\n");
    for ( each = 0; each < wordsize; each++) {// print each word
        printf ( "%s\n", words[each]);
    }
    count = 0;
    printf ( "Enter a word to search for\n");
    if ( ( scanf ( "%29[a-zA-Z]", word)) == 1) {
        for ( each = 0; each < wordsize; each++) {
            if ( strcmp ( words[each], word) == 0) {
                printf ( "Found %s at index %d\n" word, each);
                count++;
            }
        }
        printf ( "Found %s %d times\n" word, count);
    }
    for ( each = 0; each < wordsize; each++) {//release memory
        free ( words[each]);
    }
    free ( words);


    return 0;
}

如何在C中将一个字符变成一个单词

how to make a char into one word in C

c

arrays

char