Computer science AQA A-level Paper 1 Guaranteeed Success

Computer science AQA A-level Paper 1 Guaranteeed Success What is an integer? A positive or negative whole number What is a Real or Float number? What is a Boolean? What is a character? True or False A positive or negative number that can have a fractional part. A single letter, number or symbol What is a string? What is Date/Time? What is a pointer? What is a record? What is an array? A group of characters A way of storing Date/Time A way of storing a memory address. A collection of related fields, each of which could hold a different data type. A finite, indexed set of related elements of the same data type. What is a user defined data type? a customized data structure. What is variable declaration? A data type derived from existing data types in order to create Creating a variable for the first time. giving it a name and sometimes a data type. What is constant decleration? What is assignment? Creating a constant for the first time. giving a constant or a variable a value. what is iteration? repetition of a process e.g. a while or for loop. this could be definite or indefinite. What is selection? statement. what is a subroutine? comparing values and then choosing an appropriate action. e.g. an if A named block of code containing a set of instructions designed to perform a frequently used operation. What is definite iteration? What is indefinite iteration? What is a nested structure? indentation. the number of repititions is known before the loop starts. the number of repititions is not known before the loop starts. One structure is placed within another. Easily identified by What is meant by meaningful identifier names? sensible and meaningful identifier names. What does the real/float division operator do? What does the integer division operator do? the whole number part. What does the modulo operator do? Giving constants, variables and subroutines divides one number by the other. divides one number by the other but only returns returns the remainder of an integer division. What does the exponentiation operator do? What does the rounding operator do? raises one value to the power of another. limits the degree of accuracy of a number. (rounds up or down) What does the truncation operator do? removes the decimal part of a number. (never rounds up) what does the string handling function "Length" do? Returns the number of characters in a specified string. what does the string handling function "position" do? within a string. returns the position of a specified character what does the string handling function "concatenation" do? form a new and longer string. Is a function required to return a value? is a procedure required to return a value? yes no what can stack frames store for each subroutine? joins two or more strings together to Return addresses Parameters Local variables what is a recursive subroutine? a subroutine defined in terms of itself. what two conditions must a recursive subroutine meet in order for the program to run correctly. it must have a stopping condition/base case. this stopping condition must be met at some point. what type of error would occur if a base case in a recursive subroutine is never met. overflow error. what is a data type? Stack a particular kind of data item, as defined by the values it can take, the programming language used, or the operations that can be performed on it. why is it important to give meaningful identifier names? It allows a different programmer to work out the purpose of a constant, variable or subroutine from its name. what two things are data types defined by? can be performed on them. there values they can take and the operations that is -44 an integer? yes which data type can only be true or false? Boolean. in what type of iteration is the number of repititions required not known before the loop