c - 使用 switch 语句的字数统计程序在 C 中出错

Question

我无法计算用户使用 switch 语句输入的字数。我想确保多次按下键盘 (ASCII,32) 不计入多个单词。如您所见，我有一个存储上一次键盘按下的内存变量，我只想在当前键盘按下是空格和上一次按下时(即内存变量不是空格)计算一个单词。这个逻辑对我来说很有意义；但是，该代码似乎不起作用。有人可以解释我的逻辑缺陷在哪里吗？谢谢。

// 1.4 Exercise 1: output the amount of characters, number of words and number of newlines typed by the user 
// Note that the escape command on my mac is ENTER then COMMAND Z
#include <stdio.h>

int main()
{
    long characters = -1; // to exit program on my mac you must press COMMAND+Z 
    long newlines = 0;
    long words = 1; // assume the document starts with a word 

    printf("Type stuff! To exit type CTRL+D (some computers use CTRL+Z then space)\n");

    int i = 0;
    int memory = 32; //stores the previous keyboard press 


    while (i != EOF) // characters will continue counting as long as the escape sequence is not entered 
    {
        i = getchar(); //Assign the integer output of the buffered getchar() function to i 

        if (i != 10)
        {
            characters++;
        }

        switch (i)
        {
        case 10: // for enter key press
        {
            newlines++;
            break; // exit switch (each character is unique) 
        }
        case 32: // for space 
        {
            if (memory != 32) // if the previous character press was not a space, then words++
            {
                words++;
            }
            memory = i; // stores the previous keyboard press
            break; // exit switch (each character is unique) 
        }
        default: break; //exit switch is the default action if the previous switches are not true 
        }
    }

    printf("%d characters were typed\n", characters);
    printf("%d words were typed\n", words);
    printf("%d lines were typed\n", newlines);

    return 0;
}

Answer 1

当 i = 32 时，您只是在 case 语句内部更新内存值。这样，内存值将始终为 32。相反，您应该在 switch 语句关闭后更新内存值。即

switch(i)
{
    /* code here */
}
memory = i

作为旁注，如果您不将字符的 ascii 值硬编码到 switch 语句中，它将使您的代码更具可读性并有助于移植。您可以改用字符来编写它们。

switch(i) 
{
    case '\n':
        /* code */
        break;
    case ' ':
        /* code */
        break;
}