Compilare: main.cpp: In function 'int main()': main.cpp:20:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < pat.length(); ++i) { ~~^~~~~~~~~~~~~~ main.cpp:27:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < pat.length(); ++i) ~~^~~~~~~~~~~~~~ main.cpp:33:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = pat.length(); i < txt.length(); ++i) { ~~^~~~~~~~~~~~~~