E xercise 18.2.1: Below are two transactions, described in terms of their effect on two database elements A and B, which we may assume are integers. Ti: READ(A, t); t:= t+ 2 ; WRITE(A , t ) ; READ(B, t); t:= t* 3 ; WRITE(B, t); T2: READ(B, s); s:= s*2; WRITE(B, s); READ(A, s); s:=s+3; WRITE(A. s); 896 CHAPTER 18. CONCURRENCY CONTROL We assume that, whatever consistency constraints there are on the database, these transactions preserve them in isolation. Note that A = B is not the consistency constraint.

Write a method that accepts a string object as an argument and returns the number of words it contains. for instance, if the argument is "four score and seven years ago", the method should return the number 6. demonstrate the method in a program that asks the user to input a string and then passes that string into the method, printing out whatever the method returns.

Consider the following statements: #include #include class temporary { private: string description; double first; double second; public: temporary(string = "", double = 0.0, double = 0.0); void set(string, double, double); double manipulate(); void get(string& , double& , double& ); void setdescription(string); void setfirst(double); void setsecond(double); }; write the definition of the member function set() so that the instance variables are set according to the parameters. write the definition of the constructor so that it initializes the instance variables using the function set() write the definition of the member function manipulate() that returns a decimal number (double) as follows: if the value of description is "rectangle", it returns first * second if the value of description is "circle" it returns the area of a circle with radius first if the value of description is "cylinder" it returns the volume of a cylinder with radius first and height second. hint: the volume of a cylinder is simply the area of the circle at the base times the height. if the value of description is "sphere" it returns the volume of the sphere with radius first. otherwise it returns -1.0;

Which one of the following is considered a peripheral? a software b mouse c usb connector d motherboard