compress.cpp: In function 'std::vector<char, std::allocator<char> > parse()': compress.cpp:28: warning: NULL used in arithmetic compress.cpp:34: warning: comparison between signed and unsigned integer expressions compress.cpp: In function 'int main()': compress.cpp:57: warning: comparison between signed and unsigned integer expressions compress.cpp:51: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result compress.cpp:52: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result compress.cpp:55: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result /tmp/ccvO7k1i.o: In function `main': compress.cpp:(.text+0x3b1): warning: the `gets' function is dangerous and should not be used.