prodnr.cpp: In function 'int factors(int)': prodnr.cpp:21: warning: no return statement in function returning non-void prodnr.cpp: In function 'int main()': prodnr.cpp:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result prodnr.cpp:25: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result prodnr.cpp:26: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/ccq4FO2o.o: In function `main': prodnr.cpp:(.text+0xc6): warning: the `gets' function is dangerous and should not be used.