ambigram.cpp: In function 'int main()': ambigram.cpp:20: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result ambigram.cpp:21: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result ambigram.cpp:22: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result ambigram.cpp:39: warning: 'z' may be used uninitialized in this function ambigram.cpp:75: warning: 'x' may be used uninitialized in this function ambigram.cpp:75: warning: 'y' may be used uninitialized in this function /tmp/ccYIgD9K.o: In function `main': ambigram.cpp:(.text+0xdb): warning: the `gets' function is dangerous and should not be used.