Compilare: user.cpp: In function ‘int must(std::string)’: user.cpp:26:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = pos; i + patt.size() - 1 <= n; i++) { ^ user.cpp:28:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < patt.size(); j++) ^ user.cpp: In function ‘int rep(std::string)’: user.cpp:45:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = pos; i + patt.size() - 1 <= n; i += patt.size()) { ^ user.cpp:47:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < patt.size(); j++) ^ user.cpp: In function ‘int main()’: user.cpp:207:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("peg.in","r",stdin); ^ user.cpp:208:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("peg.out","w",stdout); ^ user.cpp:210:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &t); ^ user.cpp:213:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s\n", s + 1); ^