尽管未声明，C 编译器仍期望函数中存在附加参数

Question

我声明了一个带有 2 个参数的函数，并用 2 个参数调用它，但是编译器似乎将其转换为需要 FILE * __restrict 类型的附加参数的函数。

我使用的是 Mac OSX 10.11.6同时使用 cc 和 gcc 会产生相同的错误。

我应该为函数提供什么参数，或者我应该使用编译器更改设置？或者我只是错过了某个地方的拼写错误......

错误是:

longest-line.c:6:5: error: conflicting types for 'getline'
int getline(char line[], int maxline);
    ^
/usr/include/stdio.h:442:9: note: previous declaration is here
ssize_t getline(char ** __restrict, size_t * __restrict, FILE * __restrict) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);
        ^
longest-line.c:17:37: error: too few arguments to function call, expected 3, have 2
        while ((len = getline(line, MAXLINE)) > 0)
                      ~~~~~~~              ^
/usr/include/stdio.h:442:1: note: 'getline' declared here
ssize_t getline(char ** __restrict, size_t * __restrict, FILE * __restrict) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);
^
longest-line.c:28:5: error: conflicting types for 'getline'
int getline(char s[], int lim)
    ^
/usr/include/stdio.h:442:9: note: previous declaration is here
ssize_t getline(char ** __restrict, size_t * __restrict, FILE * __restrict) __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);
        ^
3 errors generated.

代码是:

#include <stdio.h>
#define MAXLINE 1000

int getline(char line[], int maxline);
void copy(char to[], char from[]);

int main()
{
    int len;                /* current line length */
    int max;                /* maximum length so far */
    char line[MAXLINE];     /* current input line */
    char longest[MAXLINE];  /* longest line saved here */

    max = 0;
    while ((len = getline(line, MAXLINE)) > 0)
        if (len > max) {
            max = len;
            copy(longest, line);
        }
    if (max > 0)  /* there was a line */
        printf("%s", longest);

    return 0;
}

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

    for (i = 0; i<lim-1 && (c=getchar()) != 'X' && c!='\n'; ++i)
        s[i] = c;
    if (c == '\n') {
        s[i] = c;
        i++;
    }
    s[i] = '\0';
    return i;
}

void copy(char to[], char from[])
{
    int i;

    i = 0;
    while ((to[i] = from[i]) != '\0')
        ++i;
}

Answer 1

getline 是一个保留名称(在 POSIX 中)，您无法顺利使用它，请更改您的函数名称。