Compilare: main.cpp: In function 'int main()': main.cpp:19:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t i = 0; i < n; i++) ~~^~~ main.cpp:38:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t i = 0; i < n; i++) ~~^~~ main.cpp:61:8: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized] o << c; ^