Compilare: user.cpp: In function ‘int main()’: user.cpp:54:12: warning: unused variable ‘k’ [-Wunused-variable] int n, k, m; ^ user.cpp:54:15: warning: unused variable ‘m’ [-Wunused-variable] int n, k, m; ^ user.cpp: In function ‘char nextch()’: user.cpp:10:36: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, BUF_SIZE, 1, fi); ^