C语言count_sentences函数条件判断报错，求非else if修复方案

尝试编写if语句检查文本中是否包含.、!或?时持续报错，出错的是count_sentences函数，原代码如下：

int count_letters(string text);
int count_words(string text);
int count_sentences(string text);

int main(void)
{
    string text = get_string("Text: ");
    printf("%s\n", text);

    int letters = count_letters(text);
    printf("%i letters\n", letters);

    int words = count_words(text);
    printf("%i words\n", words);

    int sentences = count_sentences(text);
    printf("%i sentences\n", sentences);
}

int count_letters(string text)
{
    int letters = 0;

    for (int i = 0, len = strlen(text); i < len; i++)
    {
        if (isalpha(text[i]))
        {
            letters++;
        }
    }
    return letters;
}

int count_words(string text)
{
    int words = 0;

    for (int i = 0, len = strlen(text); i < len; i++)
    {
        if (text[i] == ' ')
        {
            words++;
        }
    }
    return words + 1;
}

int count_sentences(string text)
{
    int sentences = 0;

    for (int i = 0, len = strlen(text); i < len; i++)
    {
        if (text[i] == '.' || '!' || '?')
        {
            sentences++;
        }
    }
    return sentences;
}

编译报错信息：

readability.c:66:28: error: use of logical '||' with constant operand [-Werror,-Wconstant- 
logical-operand]
        if (text[i] == '.' || '!' || '?')
                           ^  ~~~
readability.c:66:28: note: use '|' for a bitwise operation
        if (text[i] == '.' || '!' || '?')
                           ^~
                           |
fatal error: too many errors emitted, stopping now [-ferror-limit=]

已知可用else if实现，但希望用当前的逻辑或写法修复，该如何解决？

报错原因是逻辑或运算符||的使用错误：C语言中，||两侧必须是完整的布尔表达式，你当前的写法text[i] == '.' || '!' || '?'中，'!'和'?'是字符常量，会被当作非零值（恒为真），这不符合语法要求。

需要给每个符号都补充完整的判断条件，修正后的count_sentences函数如下：

int count_sentences(string text)
{
    int sentences = 0;

    for (int i = 0, len = strlen(text); i < len; i++)
    {
        if (text[i] == '.' || text[i] == '!' || text[i] == '?')
        {
            sentences++;
        }
    }
    return sentences;
}

这样每个条件都明确判断text[i]是否等于对应的标点符号，符合逻辑或的语法规则，编译即可通过。

内容的提问来源于stack exchange，提问作者Boriscodes