Compilare: main.cpp: In function 'int main()': main.cpp:141:11: warning: unused variable 'i' [-Wunused-variable] int n,i,j; ^ main.cpp:141:13: warning: unused variable 'j' [-Wunused-variable] int n,i,j; ^ main.cpp: In function 'char read_ch()': main.cpp:55:33: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(_in_buff, 1, 4096, _fin); ^