prop.cpp: In function 'int main()': prop.cpp:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result prop.cpp:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result prop.cpp:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result prop.cpp:21: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/ccdKkxR9.o: In function `main': prop.cpp:(.text+0x8e): warning: the `gets' function is dangerous and should not be used.