Eroare de compilare: main.c: In function 'main': main.c:9:9: error: redeclaration of 'r' with no linkage 9 | int r; | ^ main.c:7:15: note: previous declaration of 'r' with type 'int' 7 | int a, b, r; | ^ main.c:17:9: warning: argument 2 null where non-null expected [-Wnonnull] 17 | fprintf(output, 0); | ^~~~~~~ In file included from main.c:1: /usr/include/stdio.h:350:12: note: in a call to function 'fprintf' declared 'nonnull' 350 | extern int fprintf (FILE *__restrict __stream, | ^~~~~~~ Non zero exit status: 1