Compilare: main.cpp: In function 'BigInt Integer(std::__cxx11::string)': main.cpp:33:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<s.size();i+=9) { ~^~~~~~~~~ main.cpp: In function 'BigInt Integer(char*)': main.cpp:18:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] #define FOR(i,l,r) for (int i=l;i<=r;i++) main.cpp:44:9: FOR(i,0,strlen(c)-1) s = s + c[i]; ~~~~~~~~~~~~~~~ main.cpp:44:5: note: in expansion of macro 'FOR' FOR(i,0,strlen(c)-1) s = s + c[i]; ^~~ main.cpp: In function 'BigInt operator+(BigInt, BigInt)': main.cpp:18:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] #define FOR(i,l,r) for (int i=l;i<=r;i++) main.cpp:144:9: FOR(i,0,max(a.size(), b.size())-1) { ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:144:5: note: in expansion of macro 'FOR' FOR(i,0,max(a.size(), b.size())-1) { ^~~ main.cpp:145:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i < a.size()) carry += a[i]; ~~^~~~~~~~~~ main.cpp:146:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i < b.size()) carry += b[i]; ~~^~~~~~~~~~ main.cpp: In function 'BigInt operator-(BigInt, BigInt)': main.cpp:18:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] #define FOR(i,l,r) for (int i=l;i<=r;i++) main.cpp:180:9: FOR(i,0,a.size()-1) { ~~~~~~~~~~~~~~ main.cpp:180:5: note: in expansion of macro 'FOR' FOR(i,0,a.size()-1) { ^~~ main.cpp:181:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] carry += a[i] - (i < b.size() ? b[i] : 0); ~~^~~~~~~~~~ main.cpp: In function 'BigInt operator*(BigInt, BigInt)': main.cpp:18:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] #define FOR(i,l,r) for (int i=l;i<=r;i++) main.cpp:213:9: FOR(i,0,a.size()-1) { ~~~~~~~~~~~~~~