zigzag.cpp: In function 'int main()': zigzag.cpp:12: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result zigzag.cpp:13: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result In file included from /usr/include/stdio.h:910, from zigzag.cpp:2: In function 'char* fgets(char*, int, FILE*)', inlined from 'int main()' at zigzag.cpp:13: /usr/include/bits/stdio2.h:253: warning: call to '__fgets_chk_warn' declared with attribute warning: fgets called with bigger size than length of destination buffer