Compilare: main.cpp: In function 'int t3()': main.cpp:80:13: warning: unused variable 'val' [-Wunused-variable] int val = exp(); ^~~ main.cpp: In function 'int main()': main.cpp:109:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sir.size(); i++) ~~^~~~~~~~~~~~ main.cpp:119:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i < sir.size() - 1 && sir[i] == 'O' && sir[i + 1] == 'R') ~~^~~~~~~~~~~~~~~~ main.cpp:124:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i < sir.size() - 2 && sir[i] == 'N' && sir[i + 1] == 'O' && sir[i + 2] == 'T') ~~^~~~~~~~~~~~~~~~ main.cpp:129:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i < sir.size() - 2 && sir[i] == 'A' && sir[i + 1] == 'N' && sir[i + 2] == 'D') ~~^~~~~~~~~~~~~~~~ main.cpp:134:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i < sir.size() - 3 && sir[i] == 'T' && sir[i + 1] == 'R' && sir[i + 2] == 'U' && sir[i + 3] == 'E') ~~^~~~~~~~~~~~~~~~ main.cpp:139:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i < sir.size() - 4 && sir[i] == 'F' && sir[i + 1] == 'A' && sir[i + 2] == 'L' && sir[i + 3] == 'S' && sir[i + 4] == 'E') ~~^~~~~~~~~~~~~~~~ main.cpp: In function 'int t3()': main.cpp:99:12: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized] return val; ^~~