Compilare: user.cpp: In function ‘int main()’: user.cpp:20:22: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if (a >= 'a' && a <= 'z' || a >= 'A' && a <= 'Z') ^ user.cpp:22:77: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if (((b < 'a' || b > 'z') && (b < 'A' || a > 'Z')) && (a >= 'a' && a <= 'z' || a >= 'A' && a <= 'Z')) ^ user.cpp:10:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("text.in", "r", stdin); ^ user.cpp:11:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("text.out", "w", stdout); ^ user.cpp:13:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%c", &a); ^ user.cpp:18:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%c", &b); ^