virus.cpp: In function 'int main()': virus.cpp:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result virus.cpp:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result virus.cpp:37: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result virus.cpp:41: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result virus.cpp:57: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result virus.cpp:61: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result