A program uses a stack to hold up to 60 numeric values. The stack is implemented using two integer variables and a 1D array. The array is declared in pseudocode as shown: DECLARE ThisStack : ARRAY [1:60] OF REAL The stack operates as follows: • Global variable SP acts as a stack pointer that points to the next available stack location. The value of SP represents an array index. • Global variable OnStack represents the number of values currently on the stack. • The stack grows upwards from array element index 1.

1. (a)(i)Give the initial values that should be assigned to the two variables. SP OnStack[1]
2. (a)(ii)Explain why it is not necessary to initialise the array elements before the stack is used.[2]
3. (b)A function to add a value to ThisStack is expressed in pseudocode as shown. The function will return a value to indicate whether the operation was successful or not. Complete the pseudocode by filling in the gaps. FUNCTION Push(ThisValue : REAL) RETURNS BOOLEAN DECLARE ReturnValue : BOOLEAN IF RETURN ENDIF SP ← OnStack ← OnStack + 1 RETURN TRUE ENDFUNCTION THEN // stack is already full ThisValue[4]