Compilare: main.cpp: In function 'int main()': main.cpp:43:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i ++) { ~~^~~~~~~~~~ main.cpp:78:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < s.size() && isdigit(s[i])) { ~~^~~~~~~~~~ main.cpp:83:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i < s.size()) ~~^~~~~~~~~~ main.cpp: In function 'int compute(int, char, int)': main.cpp:35:1: warning: control reaches end of non-void function [-Wreturn-type] } ^