Compilare: user.cpp: In function ‘void bf(int)’: user.cpp:24:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[k].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:98:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[x].size();j++){ ^ In file included from /usr/include/string.h:642:0, from user.cpp:4: In function ‘void* memset(void*, int, size_t)’, inlined from ‘void bf(int)’ at user.cpp:15:30: /usr/include/i386-linux-gnu/bits/string3.h:82:32: warning: call to ‘__warn_memset_zero_len’ declared with attribute warning: memset used with constant zero length parameter; this could be due to transposed parameters [enabled by default] __warn_memset_zero_len (); ^ /tmp/ccb4OsDq.o: In function `bf(int)': user.cpp:(.text+0x248): warning: memset used with constant zero length parameter; this could be due to transposed parameters