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copied!<p>From section 7.1.3 paragraph 2 of n1570 (which is a draft of C1x):</p> <blockquote> <p>No other identifiers are reserved.</p> </blockquote> <p>This is the part that means <code>getline</code> shouldn't be defined by the <code><stdio.h></code>, since it's not a reserved identifier according to the spec. So if your library defines <code>getline</code> in <code><stdio.h></code>, it's not technically compliant with the C standard...</p> <p>However, you <em>should</em> be able to use the feature test macros to cause <code>getline</code> to be undefined in <code><stdio.h></code>.</p> <pre><code>#undef _POSIX_C_SOURCE #define _POSIX_C_SOURCE 200112L #include <stdio.h> </code></pre> <p>This will give you only the definitions from the older POSIX standards. This won't work on some GNU C++ implementations, which is <strong>ExTrEmeLY fruSTRaTiNG</strong> for some folks.</p> <p>The relevant section of the manpage is (taken from a glibc manpage, sorry...)</p> <pre> Feature Test Macro Requirements for glibc (see feature_test_macros(7)): getline(), getdelim(): Since glibc 2.10: _POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700 Before glibc 2.10: _GNU_SOURCE </pre> <p>This part of the manpage tells you which macros need to be defined to which values in order to get the definition. My bet is that <code>_POSIX_C_SOURCE</code> is already defined by your compiler to <code>200809L</code>.</p> <p>The idea of feature test macros is that if you define your macros, like <code>_POSIX_C_SOURCE</code>, <code>_BSD_SOURCE</code>, <code>_XOPEN_SOURCE</code>, etc. to the values you want, you won't need to worry about new library functions clashing with your existing functions. There is also <code>_GNU_SOURCE</code>, which turns <em>everything</em> on if you use glibc, but I suggest giving that macro a wide berth.</p>

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