Compilare: user.cpp: In function ‘int main()’: user.cpp:10:15: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(u>='A' && u<='Z' || u>='a' && u<='z') ^ user.cpp:17:21: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(!(l>='A' && l<='Z' || l>='a' && l<='z')) ^ user.cpp:23:21: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(!(u>='A' && u<='Z' || u>='a' && u<='z')) ^