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()$c$c>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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