K＆安培; R第2版，例1.9字符数组 [英] K&R 2nd Edition, Example 1.9 Character Arrays

问题描述

我有在以下code问候则对getline（）函数和参数的定义的问题。在code是直接从K＆放取; R 1.9章：字符数组。我已复制在这里一字不差。问题是，当我编译程序的是我得到三个错误，（我在年底纷纷转载）。当我在三个地方我得到的错误更改功能，和功能参数定义get_line（）（带有下划线，而不是仅仅函数getline），错误停止，程序运行正常。

I have a question in regards to the getline() function and parameter definition in the following code. The code is taken directly from K&R chapter 1.9: "Character arrays". I have reproduced it here verbatim. The issue is that when I compile the program as is I get three errors,(which I have reproduced at the end). When I change the function, and the function parameter definition to get_line() (with an underscore instead of just getline) in the three places where I get the errors, the errors stop and the program runs as expected.

我的问题是：

#include <stdio.h>
#define MAXLINE 1000    // maximum input line size

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

/* print longest input line */

int main()
{
    int len;            //current line lenght
    int max;            //maximum length seen 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;
}

/*  getline: read a line into s, return length */
int getline(char s[], int lim)
{
    int c, i;

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


/* copy: copy 'from' into 'to'; assume to is big enough */
void copy(char to[],char from[])
{
    int i;

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

我得到的错误是：

The errors I get are:

• ./部分1.9.1.c：4：5：错误：冲突的类型'函数getline';
  INT函数getline（INT线[]，INT MAXLINE）;

./部分1.9.1.c：17：40：错误：太少参数函数调用，预计3，有2个
，而（（LEN =函数getline（线，MAXLINE））0）; 和

./section 1.9.1.c:17:40: error: too few arguments to function call, expected 3, have 2 while ((len = getline(line, MAXLINE)) > 0); and

./部分1.9.1.c：30：5：错误：冲突的类型'函数getline
INT函数getline（int类型[]，INT LIM）

./section 1.9.1.c:30:5: error: conflicting types for 'getline' int getline(int s[], int lim)

推荐答案

与的glibc 分布式stdio库声明一个是也被称为函数函数getline 有比你不同的签名。既然你不能使用相同的名称声明两个函数编译器提供了一个错误。 函数getline 的相互矛盾的声明在stdio.h发现的是：

The stdio library distributed with glibc declares a function that is also called getline with a different signature than yours. Since you cannot declare two functions with the same name the compiler gives an error. The conflicting declaration of getline found in stdio.h is:

   ssize_t getline(char **lineptr, size_t *n, FILE *stream);

的函数getline 功能原本是glibc的扩展，并且再被列入POSIX.1-2008。 这是不是一个标准的C函数。

The getline function was originally a glibc extension, and has then been included in POSIX.1-2008. It is not a standard C function.

如果您使用的是 GCC 您可以通过使用 -std 命令行开关获得符合标准的行为。别的不说这个隐藏非标准函数的声明。尝试例如：

If you are using gcc you can get standards-compliant behavior by using the -std command line switch. Among other things this hides declarations of non-standard functions. Try for example:

gcc -Wall -pedantic -std=c11 "section 1.9.1.c" -o "section 1.9.1"

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