Compilare: user.cpp: In function ‘int main()’: user.cpp:12:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<s2.length();j++){ ^ user.cpp:13:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while((s2[j]!=s1[i])&&(i<s1.length())) i++; ^ user.cpp:7:28: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sr.in","r",stdin); ^ user.cpp:8:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sr.out","w",stdout); ^