Question

我正在尝试编写一个程序，将每个单词的长度存储在排列并打印。但是不会打印长度n，而是打印长度n - 1。

#include <stdio.h>

#define IN 1
#define OUT 0
#define MAXLENGTH 10

int main(void)
{
    int i, c, state, word;
    int array[MAXLENGTH];

    state = OUT;
    word = 0;

    for (i = 0; i < MAXLENGTH; i++)
        array[i] = 0;

    while ((c = getchar()) != EOF)
    {
        if (c == '\n' || c == ' ')
            state = OUT;
        else if (state == IN)
        {
            ++array[word];
        }
        else if (state == OUT)
        {
            state = IN;
            ++word;
        }
    }

    for (i = 1; i < MAXLENGTH; i++)
        if (array[i] != 0)
            printf("cuvantu %d are %d caractere \n", i, array[i]);
}

Answer 1

考虑以下代码：

    if (c == '\n' || c == ' ')
        state = OUT;
    else if (state == IN)
    {
        ++array[word];
    }
    else if (state == OUT)
    {
        state = IN;
        ++word;
    }

当c是换行符或空格时，它将状态更改为OUT，大概是在单词之外。

当c是另一个字符时：

如果状态为IN，它将通过递增array[word]来计数字符，该字符将跟踪当前单词的长度。
如果状态为OUT，它将状态更改为IN，并递增word以开始对新单词计数。

在最后一种情况下，不计算当前字符-不执行对array[word]的递增。要解决此问题，请在最后一种情况下插入++array[word];：

    if (c == '\n' || c == ' ')
        state = OUT;
    else if (state == IN)
    {
        ++array[word];
    }
    else if (state == OUT)
    {
        state = IN;
        ++word;
        ++array[word];
    }

Answer 2

这似乎是避免常见的一次性错误的好方法。

虽然可以通过多种方式解决，但以下代码段显示了如何修改发布状态机的逻辑，以便可以从头开始填充长度数组，而无需跳过第一个元素array[0]，达到（但不超过）其最大大小。

#include <stdio.h>

#define IN 1
#define OUT 0
#define MAXLENGTH 16

int main(void)
{
    int array[MAXLENGTH] = {0};

    int c, state = OUT,   
        n_words = 0; //  <-- this name may better convey the purpose of this variable

    while ((c = getchar()) != EOF)
    {
        if (c == '\n' || c == ' ')  // <-- Consider isspace() and iscntrl() instead.
        {
            // We are between words.
            state = OUT;
        }
        else
        {
            // Check the current state before updating it.
            if ( state == OUT )
            {
                // A new word starts, but there might not be enough space.
                if ( n_words == MAXLENGTH )
                {
                    // Here, the rest of the stream is not consumed
                    ungetc(c, stdin);
                    break;     
                }
                ++n_words; 
            }
            state = IN;

            // Array indices are zero based, so the current word is:
            ++array[n_words - 1];
        }
    }

    if ( c != EOF )
        fprintf(stderr, "Sorry, out of space.\n");

    // You can use the actual number of read words to limit the extent of the loop
    printf(" %5s  %5s\n---------------\n", "Word", "Length");
    for (int i = 0; i < n_words; i++)
        printf("%5d  %5d\n", i + 1, array[i]);
}

该代码是可测试的here。

Answer 3

尝试将第二个for循环更改为- for (i = 0; i < MAXLENGTH; i++)

为什么数组元素存储n-1而不是n的值

3 个答案: