Compilare: user.cpp: In function ‘void preproc()’: user.cpp:32:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<strlen(s); i++) ^ user.cpp: In function ‘int main()’: user.cpp:51:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<strlen(s); i++) ^ user.cpp:43:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefixe.in","r",stdin); ^ user.cpp:44:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefixe.out","w",stdout); ^ user.cpp:45:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&tt); ^ user.cpp:48:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",s); ^