CS 149 Chapter 2
What is the value of trouble if you assign 1/4 to it? Write your answer with two decimal places (e.g., 1.23).
0.00
What is the value of 1 + 2 * 3 - 4 in Java?
3
expression
A combination of variables, operators, and values that represents a single value. Expressions also have types, as determined by their operators and operands.
floating-point
A data type that represents numbers with an integer part and a fractional part. In Java, the default floating-point type is double.
memory diagram
A graphical representation of the state of a program at a point in time.
variable
A named storage location for values. All variables have a type, which is declared when the variable is created.
value
A number, string, or other data that can be stored in a variable. Every value belongs to a type (for example, int of String).
keyword
A reserved word used by the compiler to analyze programs. You cannot use keywords (like public, class, and void) as variable names.
declaration
A statement that creates a new variable and specifies its type.
assignment
A statement that gives a value to a variable.
operator
A symbol that represents a computation like addition, multiplication, or string concatenation.
logic error
An error in a program that makes it doe something other than what the programmer intended.
run-time error
An error in a program that makes it impossible to run to completion. Also called an "exception".
compile-time error
An error in the source code that makes it impossible to compile. Also called a "syntax error".
Where else in the book (besides Chapter 2) can you find advice about syntax errors?
Appendix D
What is the value of "Hello" + 1 + 2 in Java?
Hello12
type
Mathematically speaking, a set of values. The type of a variable determines which values it can have.
operand
One of the values on which an operator operates. Most operators in Java require two operands.
What is the main problem with floating-point numbers?
Rounding errors lead to incorrect results.
rounding error
The difference between the number we want to represent and the nearest floating-point number.
order of operations
The rules that determine in what order expressions are evaluated. Also known as "operator precedence".
state
The variables in a program and their current values.
parse
To analyze the structure of a program; what the compiler does first.
initialize
To assign a variable for the first time.
concatenate
To join two values, often strings, end-to-end.
Which of the following statements may cause a run-time error? area = x + y; area = x / y; area = x - y; area = x * y;
area = x / y;
Write a Java statement that declares a variable named trouble with type double.
double trouble;
What is the main problem with this mathematical statement? 1 + 2 # 3 ~ its semantics ~ its solution ~ its style ~ its syntax
its syntax
When the compiler says "reached end of file while parsing", what is most likely the problem?
missing brace
What is the state diagram for the following assignments? (after the code runs) name = "Anna"; pin = 1234; year = 2000; pin = year;
name [Anna] pin [2000] year [2000]
Which of the following statements is a syntax error? ~ char c; ~ double d; ~ int i; ~ string s;
string s;
Why doesn't the following code compile? public static void main(String[] args) { x = 1.23; System.out.println(x + "/n"); }}
x has not been declared
