sumb.cpp: In function 'int main()': sumb.cpp:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sumb.cpp:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sumb.cpp:36: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result sumb.cpp:44: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result sumb.cpp:52: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/ccCLYYOb.o: In function `main': sumb.cpp:(.text+0x135): warning: the `gets' function is dangerous and should not be used.