Compilare: user.c: In function ‘main’: user.c:12:23: warning: unused variable ‘ch’ [-Wunused-variable] char letters[200001], ch; ^ user.c:12:6: warning: unused variable ‘letters’ [-Wunused-variable] char letters[200001], ch; ^ user.c:11:15: warning: unused variable ‘theE’ [-Wunused-variable] int theW = 0, theE = 0; ^ user.c:11:5: warning: unused variable ‘theW’ [-Wunused-variable] int theW = 0, theE = 0; ^ user.c:10:41: warning: unused variable ‘c’ [-Wunused-variable] int i, j, N, swaps = 0, a = -1, b = -1, c = -1; ^ user.c:10:33: warning: unused variable ‘b’ [-Wunused-variable] int i, j, N, swaps = 0, a = -1, b = -1, c = -1; ^ user.c:10:25: warning: unused variable ‘a’ [-Wunused-variable] int i, j, N, swaps = 0, a = -1, b = -1, c = -1; ^ user.c:10:14: warning: unused variable ‘swaps’ [-Wunused-variable] int i, j, N, swaps = 0, a = -1, b = -1, c = -1; ^ user.c:10:11: warning: unused variable ‘N’ [-Wunused-variable] int i, j, N, swaps = 0, a = -1, b = -1, c = -1; ^ user.c:10:8: warning: unused variable ‘j’ [-Wunused-variable] int i, j, N, swaps = 0, a = -1, b = -1, c = -1; ^ user.c:10:5: warning: unused variable ‘i’ [-Wunused-variable] int i, j, N, swaps = 0, a = -1, b = -1, c = -1; ^ user.c:9:7: warning: variable ‘file1’ set but not used [-Wunused-but-set-variable] FILE *file1, *file2; ^