C语言中支持单字母输入的Wordcount

Question

我在 'wordcount' 正确计数时遇到了一些问题，因为它错过了 'I' 等单数字母。

本质上，如果 space 在 character/symbol 或独立 character/symbol 之间，将计算一个字数。

#include <stdio.h>

int main()
{
    int wordcount;
    int ch;
    char lastch = -1;

    wordcount = 0;

    while ((ch = getc(stdin)) != EOF) {
        if (ch == ' ' || ch == '\n')
        {
            if (!(lastch == ' ' && ch == ' '))
            {
                wordcount++;
            }
        }
        lastch = ch;
    }

    printf("The document contains %d words.", wordcount);
}

Answer 1

您使条件测试过于复杂。如果我理解您的目的，您唯一关心的是 lastch != ' ' 和 (ch == ' ' || ch == '\n').

此外，getchar returns 输入 int。因此，ch 应键入 int 以在所有系统上正确检测 EOF。

通过这些更改进行简化，您可以执行类似以下操作：

#include <stdio.h>

int main (void) {

    int wordcount = 0,
        lastch = 0,     /* just initialize to zero */
        ch;             /* ch should be an int */

    while ((ch = getc (stdin)) != EOF) {
        if (lastch && lastch != ' ' && (ch == ' ' || ch == '\n'))
            wordcount++;
        lastch = ch;
    }
    if (lastch != '\n') /* handle no '\n' on final line */
        wordcount++;

    printf ("The document contains %d %s.\n", 
            wordcount, wordcount != 1 ? "words" : "word");

    return 0;
}

例子Use/Output

$ echo "     " | ./bin/wordcnt
The document contains 0 words.

$ echo "   t  " | ./bin/wordcnt
The document contains 1 word.

$ echo "   t t  " | ./bin/wordcnt
The document contains 2 words.

注意： 以防止不包含 POSIX eof 的文件的极端情况（例如 '\n' 在文件末尾），您需要添加一个额外的标志，表明至少找到一个字符，并在退出循环后组合检查 lastch，例如

#include <stdio.h>

int main (void) {

    int wordcount = 0,
        lastch = 0,     /* just initialize to zero */
        ch,             /* ch should be an int */
        c_exist = 0;    /* flag at least 1 char found */

    while ((ch = getc (stdin)) != EOF) {
        if (lastch && lastch != ' ' && (ch == ' ' || ch == '\n'))
            wordcount++;
        if (ch != ' ' && ch != '\n')    /* make sure 1 char found */
            c_exist = 1;
        lastch = ch;
    }
    if (c_exist && lastch != '\n')  /* handle no '\n' on final line */
        wordcount++;

    printf ("The document contains %d %s.\n", 
            wordcount, wordcount != 1 ? "words" : "word");

    return 0;
}

极端案例

$ echo -n "   t" | ./bin/wordcnt
The document contains 1 word.

C语言中支持单字母输入的Wordcount

Wordcount in C that supports singlar letter input

c

getchar