concat.cpp: In function 'void bkt(std::string)': concat.cpp:25: warning: comparison between signed and unsigned integer expressions concat.cpp: In function 'int main()': concat.cpp:49: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x concat.cpp:49: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x concat.cpp:55: warning: comparison between signed and unsigned integer expressions