c - 为什么我会得到如此困惑的输出？

Question

我正在编写一个程序来打印出现的字母和(一个、两个、三个字母等)单词。到目前为止，我已经让字母部分正常工作，但我根本无法让单词部分正常工作，更不用说区分一个、两个或三个字母的单词了。我试图找出程序出错的地方，似乎是在我尝试将它们存储在数组“word”中的时候。

有人建议使用 strlok() 但没有提及如何使用。

编辑:我用 sizeof() 替换了 strlen() 并将我的“i”变量设置为 0，但我的输出仍然是整个字符串的第一个字母和一些奇怪的字符。

#include <stdio.h>
#include <string.h>
#include <ctype.h>
void findLetters(char *ptr);
void findWords(char *point);


int main()
{
    char textStream[100]; //up to 98 characters and '\n\ and '\0'

    printf ( "enter some text\n");
    if ( fgets( textStream, sizeof ( textStream), stdin)) //input up to 99 characters
    {
        findLetters(textStream);
    }
    else
    {
        printf ( "fgets failed\n");
    }
    findWords(textStream);
    return 0;
}

void findLetters(char *ptr) //find occurences of all letters
{
    int upLetters[26];
    int loLetters[26];
    int i;
    int index;

    for ( i = 0; i < 26; i++) // set array to all zero
    {
        upLetters[i] = 0;
        loLetters[i] = 0;
    }
    i = 0;
    while ( ptr[i] != '\0') // loop until prt[i] is '\0'
    {
        if (ptr[i] >= 'A' && ptr[i] <= 'Z') //stores occurrences of uppercase letters
        {
            index = ptr[i] - 'A';// subtract 'A' to get index 0-25
            upLetters[index]++;//add one
        }

        if (ptr[i] >= 'a' && ptr[i] <= 'z') //stores occurrences of lowercase letters
        {
            index = ptr[i] - 'a';//subtract 'a' to get index 0-25
            loLetters[index]++;//add one
        }
        i++;//next character in ptr
    }
    printf("Number of Occurrences of Uppercase letters\n\n");
    for ( i = 0; i < 26; i++)//loop through 0 to 25
    {
        if ( upLetters[i] > 0)
        {
            printf("%c : \t%d\n", (char)(i + 'A'), upLetters[i]);
            // add 'A' to go from an index back to a character
        }
    }
    printf("\n");
    printf("Number of Occurrences of Lowercase letters\n\n");
    for ( i = 0; i < 26; i++)
    {
        if ( loLetters[i] > 0)
        {
            printf("%c : \t%d\n", (char)(i + 'a'), loLetters[i]);
            // add 'a' to go back from an index to a character
        }
    }
}

void findWords(char *point)
{
    int i = 0; 
    int k = 0; 
    int count = 0;
    int j = 0; 
    int space = 0;
    int c = 0;
    char word[50][100], word1[50][100];

    for (;i < sizeof(point);i++) //counts # of spaces between words
    {
        if ((point[i] == ' ')||(point[i] == ',')||(point[i] == '.'))
        {
            space++;
        }
    }
    i = 0; 
    for(; i < sizeof(point); i++) //seperates strings from each other
    {
        if(point[i] == '.' || point[i] == 44|| point[i] == 46)
        {
            word[j][k] = '\0';
            j++;
            k = 0;
            printf("%s\n",point[i]);
        }
        else
        {
            word[j][k] = point[i];
            k++;
        }
        printf("%s\n",word[j]);
    }
    k = 0;

    for (i = 0;i <= space;i++) 
    {
        for (j = 0;j <= space;j++) 
        {
            if (i == j) // finds occurrences of words
            {
                strcpy(word1[k], word[i]); //copies words in new array
                k++;
                count++;

            } 
            else if(strcmp(word1[j], word[i]) != 0) //makes sure that the word copied equals the word from the string
            {
                ;
            }
        }
    }
    j = 0;
    i = 0;
    for (;i < count ;i++) 
    {
        for (;j <= space;j++)
        {
            if (strcmp(word1[i], word[j]) == 0) //counts occurrence of each word
            {
                c++;
            }
        }
        printf("%s \t %d times\n", word1[i], c);
        c = 0;
    }
}

Answer 1

你的代码有几个问题:

• for(;i < strlen(point); i++) //seperates strings from each other执行此行时 i 的值已经是strlen因此以下 for没有被执行。添加i=0要解决这个问题。

• 你应该使用 sizeof不要 strlen，否则你会错过最后一个词。

• if(point[i] == '.' || point[i] == 44|| point[i] == 46)你没有检查 ' '这里。正确的 if 条件应该是: if(point[i] == ' ' || point[i] == '.'|| point[i] == ' ')

• 您的代码没有考虑同时使用逗号和空格的情况。

• 您用于在数组中查找单词的算法存在缺陷。 你应该使用这样的东西:

how_many_times(word[i], word, number_of_words);

int how_many_times(char * word, char words[50][100], int how_many_words) {
  int i = 0, counter=0;                                                                         
  for (i=0; i< how_many_words; i++) {
    if ( strcmp(words[i], word) == 0 ) {
      counter++;
    }
  } 
  return counter;
}