undefined reference to `getline' in c

Question

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

#include 
#include <         


        

Answer 1

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.

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.

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

Answer 2

getline isn't a standard function, you need to set a feature test macro to use it, according to my man page,

_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700

for glibc 2.10 or later,

_GNU_SOURCE

before that.

Answer 3

I am also using MinGW. I checked MinGW headers and getline() does not appear in any C header, it appears only in C++ headers. This means the C function getline() does not exist in MinGW.