Compilare: main.cpp: In function 'int main()': main.cpp:22:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (isalpha(s[j]) && j < s.size()) aux += s[j], ++j; ~~^~~~~~~~~~ main.cpp:23:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[j] == ' ' && j < s.size()) ++j; ~~^~~~~~~~~~ main.cpp:24:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (isdigit(s[j]) && j < s.size()) num = num * 10 + s[j] - '0', ++j; ~~^~~~~~~~~~ main.cpp:30:54: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (!(isdigit(s[j])) && j < s.size()) ++j; ~~^~~~~~~~~~ main.cpp:31:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (isdigit(s[j]) && j < s.size()) num = num * 10 + s[j] - '0', ++j; ~~^~~~~~~~~~