Compilare: user.c: In function ‘main’: user.c:10:25: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z') ^ user.c:5:12: warning: unused variable ‘d’ [-Wunused-variable] char c,d; ^