Compilare: main.cpp: In function 'int main()': main.cpp:54:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t i = 1; i <= n; i++) ~~^~~~ main.cpp: In function 'char read(FILE*)': main.cpp:21:27: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buffer, 1, len, f); ^