In file included from /usr/include/c++/4.4/unordered_map:35, from perm.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. perm.cpp:12: error: ISO C++ forbids declaration of 'unordered_map' with no type perm.cpp:12: error: expected ';' before '<' token perm.cpp: In function 'void Insert(Trie_nod*, char*, int)': perm.cpp:29: error: 'struct Trie_nod' has no member named 'next' perm.cpp:30: error: 'struct Trie_nod' has no member named 'next' perm.cpp:40: error: 'struct Trie_nod' has no member named 'next' perm.cpp: In function 'int Find(Trie_nod*, char*)': perm.cpp:49: error: 'struct Trie_nod' has no member named 'next' perm.cpp: In function 'void DFS(Trie_nod*, Trie_nod*, int, int)': perm.cpp:66: error: 'struct Trie_nod' has no member named 'next' perm.cpp: In function 'int main()': perm.cpp:73: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result perm.cpp:74: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result perm.cpp:82: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result perm.cpp:84: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result perm.cpp:89: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result perm.cpp:91: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result