prodnr.cpp: In function 'int main()': prodnr.cpp:8: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result prodnr.cpp:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result prodnr.cpp:11: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/ccnOTWRM.o: In function `main': prodnr.cpp:(.text+0x5b): warning: the `gets' function is dangerous and should not be used.