foo.cpp: In member function 'void Expr::init()':
foo.cpp:50:31: error: 'stdin' was not declared in this scope
foo.cpp:50:36: error: 'fgets' was not declared in this scope
foo.cpp:52:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
foo.cpp: In function 'int main()':
foo.cpp:103:27: error: 'stdin' was not declared in this scope
foo.cpp:103:32: error: 'fgets' was not declared in this scope
foo.cpp:104:24: error: 'sscanf' was not declared in this scope
foo.cpp:114:31: warning: name lookup of 'i' changed [enabled by default]
foo.cpp:105:13: warning:   matches this 'i' under ISO standard rules [enabled by default]
foo.cpp:108:17: warning:   matches this 'i' under old rules [enabled by default]