未定义的引用`函数getline'在C [英] undefined reference to `getline' in c

问题描述

我学习C语言编程用函数getline，并试图在codeS由的http：/ /crasseux.com/books/ctutorial/getline.html

I am learning to use getline in C programming and tried the codes from http://crasseux.com/books/ctutorial/getline.html

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int atgc, char *argv[])
{
    int bytes_read = 1;
    int nbytes = 10;
    char *my_string;

    my_string = (char *)malloc(nbytes+1);

    puts("Please enter a line of text");

    bytes_read = getline(&my_string, &nbytes, stdin);

    if (bytes_read == -1)
    {
        puts ("ERROR!");
    }
    else
    {
        puts ("You typed:");
        puts (my_string);
    }

    return 0;
 }

然而，问题是，编译器保持这个返回错误：未定义引用函数getline 。
你能告诉我是什么问题？谢谢！

However, the problem is that the compiler keeps returning errors of this: undefined reference to 'getline'. Could you please tell me what the problem is? Thank you!

我使用的Win7 64位+ Eclipse的靛蓝+的MinGW

I am using Win7 64bit + Eclipse Indigo + MinGW

推荐答案

其他答案已经涵盖了大多数的这一点，但有几个问题。首先，<一个href=\"http://pubs.opengroup.org/onlinepubs/9699919799/functions/getdelim.html\"><$c$c>getline()是不是在C标准库，但它是一个POSIX 2008扩展。通常情况下，这将是可用与POSIX的兼容的编译器，作为宏_POSIX_C_SOURCE将用适当的值来定义。你可能有一个从旧的编译器之前函数getline（）是标准化的，在这种情况下，这是一个GNU扩展，并且必须的#define _GNU_SOURCE 在的#include＆LT;文件stdio.h方式＆gt; 来启用它，并且必须使用GNU兼容的编译器，如gcc

The other answers have covered most of this, but there are several problems. First, getline() is not in the C standard library, but is a POSIX 2008 extension. Normally, it will be available with a POSIX-compatible compiler, as the macros _POSIX_C_SOURCE will be defined with the appropriate values. You possibly have an older compiler from before getline() was standardized, in which case this is a GNU extension, and you must #define _GNU_SOURCE before #include <stdio.h> to enable it, and must be using a GNU-compatible compiler, such as gcc.

此外，的nbytes 的类型应该是为size_t ，而不是 INT 。在我的系统，至少，这些都是不同的大小，用为size_t 是更长的时间，并使用为int * 代替一个的为size_t * 可有严重的后果（也不能使用默认设置的gcc编译）。见，则对getline手册页（http://linux.die.net/man/3/getline）了解详情。

Additionally, nbytes should have type size_t, not int. On my system, at least, these are of different size, with size_t being longer, and using an int* instead of a size_t* can have grave consequences (and also doesn't compile with default gcc settings). See the getline manual page (http://linux.die.net/man/3/getline) for details.

随着这种变化做出，你的程序编译和我的系统上运行正常。

With that change made, your program compiles and runs fine on my system.

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