Compilare: user.cpp: In function ‘char* bignum_print(bignum)’: user.cpp:41:12: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings] return ""; ^ user.cpp: In function ‘std::vector<char>& bignum_mul(bignum, long long unsigned int)’: user.cpp:58:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.size(); i++) { ^ user.cpp:61:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < y.size(); j++) { ^ user.cpp:72:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size() + b.size(); i++) { ^ user.cpp:75:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < randuri.size(); i++) { ^ user.cpp:76:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < randuri[i].size(); j++) { ^ user.cpp:80:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < result.size(); i++) { ^