Compilare: main.cpp: In function 'int main()': main.cpp:27:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 2; i < a.size(); ++i) { ~~^~~~~~~~~~ main.cpp:30:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i + z[i] < a.size() && a[i+z[i]] == a[1+z[i]]) ++ z[i]; ~~~~~~~~~^~~~~~~~~~ main.cpp:9:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("strmatch.in", "r", stdin); ^ main.cpp:10:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("strmatch.out", "w", stdout); ^