Compilare: main.cpp: In function 'void ExpEval()': main.cpp:41:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ~~^~~~~~~~~~ main.cpp:50:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( i < s.size() - 3 && s[i] == 'T' && s[i + 1] == 'R' && s[i + 2] == 'U' ) ~~^~~~~~~~~~~~~~ main.cpp:56:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( i < s.size() - 4 && s[i] == 'F' && s[i + 1] == 'A' && s[i + 2] == 'L' ) ~~^~~~~~~~~~~~~~ main.cpp:93:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( i < s.size() - 3 && s[i] == 'N' && s[i + 1] == 'O' ) ~~^~~~~~~~~~~~~~ main.cpp:98:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( i < s.size() - 3 && s[i] == 'A' && s[i + 1] == 'N' ) ~~^~~~~~~~~~~~~~ main.cpp:103:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( i < s.size() - 2 && s[i] == 'O' && s[i + 1] == 'R' ) ~~^~~~~~~~~~~~~~ main.cpp: In function 'int Operate(int, int, char)': main.cpp:26:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ main.cpp: In function 'int Priority(char)': main.cpp:34:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ main.cpp: In function 'void ExpEval()': main.cpp:31:5: warning: 'ope' may be used uninitialized in this function [-Wmaybe-uninitialized] if( OP == '&' ) return 2; ^~ main.cpp:91:14: note: 'ope' was declared here char ope; ^~~