On 15 November 2013 19:55, ballsystemlord wrote: > I'm using C and I decided to read the whole gcc info manual and I wanted to > know, what is "__THROW" In what context? That doesn't appear in my copy of the gcc info manual. The most likely answer is that you're looking at some system headers where it is defined as a macro indicating the function never throws exceptions. That could be defined like so: #ifdef __cplusplus #define __THROW throw() #elif __GNUC__ #define __THROW __attribute__((nothrow)) #else #define __THROW #endif In C++ code that can be represented i.e. the equivalent of an empty exception specification in C++: throw()