Compilare: user.cpp: In function ‘void readData()’: user.cpp:31:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ", &r, &c); ^ user.cpp:33:23: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a[i] + 1); ^ In file included from /usr/include/stdio.h:934:0, from /usr/include/c++/4.8/cstdio:42, from user.cpp:5: In function ‘char* gets(char*)’, inlined from ‘void readData()’ at user.cpp:33:23: /usr/include/i386-linux-gnu/bits/stdio2.h:230:28: warning: call to ‘__gets_warn’ declared with attribute warning: please use fgets or getline instead, gets can't specify buffer size [enabled by default] return __gets_warn (__str); ^ /tmp/ccTvKXlX.o: In function `readData()': user.cpp:(.text+0x45): warning: the `gets' function is dangerous and should not be used.