Compilare: user.c: In function ‘main’: user.c:24:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%*c%d%*c", &n, &m); ^ user.c: In function ‘flip_row’: user.c:67:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.c: In function ‘flip_col’: user.c:76:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.c: In function ‘read_matrix’: user.c:108:12: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(from, "%d%*c", &t); ^ user.c:125:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.c: In function ‘get_empty’: user.c:176:1: warning: control reaches end of non-void function [-Wreturn-type] } ^