Compilare: user.cpp: In function ‘int main()’: user.cpp:98:29: warning: NULL used in arithmetic [-Wpointer-arith] if(postfix[i].op != NULL){ ^ user.cpp: In function ‘bool isOperator(char)’: user.cpp:25:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:32:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.in","r",stdin); ^ user.cpp:33:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.out","w",stdout); ^