In file included from /usr/include/c++/4.4/unordered_map:35, from spp.cpp:3: /usr/include/c++/4.4/c++0x_warning.h:31:2: error: #error This file requires compiler and library support for the upcoming ISO C++ standard, C++0x. This support is currently experimental, and must be enabled with the -std=c++0x or -std=gnu++0x compiler options. spp.cpp: In member function 'char InParser::read_ch()': spp.cpp:19: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result spp.cpp: At global scope: spp.cpp:75: error: expected constructor, destructor, or type conversion before '<' token spp.cpp: In function 'void depthfirst(int)': spp.cpp:88: error: 'M' was not declared in this scope spp.cpp: In function 'int main()': spp.cpp:105: error: 'M' was not declared in this scope