Compilare: user.cpp: In function ‘void prefix()’: user.cpp:11:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=2;i<=strlen(p);i++) ^ user.cpp: In function ‘int main()’: user.cpp:30:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=2;i<=strlen(t);i++) ^ user.cpp:36:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k==strlen(p)-1) ^ user.cpp:22:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("p.in","r",stdin); ^ user.cpp:23:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("p.out","w",stdout); ^ user.cpp:24:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(t+1); ^ user.cpp:26:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(p+1); ^ /tmp/cc7DPUxL.o: In function `main': user.cpp:(.text.startup+0x5b): warning: the `gets' function is dangerous and should not be used.