c - 此代码是否 ungetch() '\n' ？

Question

我到处寻找，但找不到答案!我正在使用 K&R C 书籍中的一个名为 getop 的函数进行练习。例如，当我输入 123 时，代码会检查输入的每个元素，并在它不是数字时停止。在此示例中为“\n”；它会取消 eclipse 刻( '\n' )吗？

int getop(char s[])
{
    int i, c;

    while ((s[0] = c = getch()) == ' ' || c == '\t')
        ;
    s[1] = '\0';
    if (!isdigit(c) && c != '.')
        return c; /* not a number */
    i = 0;
    if (isdigit(c)) /*collect integer part*/
        while (isdigit(s[++i] = c = getch()))
            ;
    if (c == '.') /*collect fraction part*/
        while (isdigit(s[++i] = c = getch()))
            ;
    s[i] = '\0';
    if (c != EOF)
        ungetch(c);
    return NUMBER;
}

取消 eclipse 刻功能:

void ungetch(int c) {
    if(bufp < MAXBUF) {
        printf("ungetch has been called\n");
        buf[bufp++] = c;
    }   
    else 
        printf("the buffer is full\n");
}

Answer 1

I thought that eof is for window ctrl+z , and '\n' is something else...?

ISO/IEC 9899、编程语言 - C:

EOF ... expands to an integer constant expression, with type int and a negative value, that is returned by several functions to indicate end-of-file, that is, no more input from a stream

Windows 上的 Ctrl-Z 是一个输入键组合，不会返回更多字符，甚至不会返回与 Ctrl-Z (0x1A) 等效的字符。

\n (new line) Moves the active position to the initial position of the next line.

关于原来的问题:由于负值 EOF 与任何 (unsigned char) 值不同，是的，这段代码确实执行了 ungetch() '\n'。