Compilare: main.cpp: In function 'int main(int, const char**)': main.cpp:36:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < str1.size(); ++ i){ ~~^~~~~~~~~~~~~ main.cpp:50:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = str1.size(); i < str2.size(); ++ i){ ~~^~~~~~~~~~~~~