1. Department of Computer Science
COM S 207
Variable Scope
Instructor: Ying Cai
Department of Computer Science
Iowa State University

2. The scope of a variable is the part of the program in which it is visible
public static void main(String[] args) {
System.out.println(cubeVolume(10)); }
public static double cubeVolume(double sideLength)
return sideLength * sideLength * sideLength;
the scope of the parameter sideLength is the entire cubeVolume method, but not the main method

3. Local variable: A variable that is defined within a method
public static void main(String[] args) {
int sum = 0;
for (int i=0; i<=10; i++)
int square = i * i;
sum = sum + square; }
System.out.println(sum);
The scope of a local variable ranges from its declaration until the end of the bloack or for statement in which it is declared.

4. An example of a scope problem
public static void main(String[] args) {
double sideLength = 10;
int result = cubeVolume(();
System.out.println(result); }
public static double cubeVolume()
return sideLength * sideLength * sideLength;
trying to reference a variable defined outside of the method body

5. The same variable name may be used more than once
public static void main(String[] args) {
int result = square(3) + square(4);
System.out.println(result); }
public static int square(int n)
int result = n * n;
return result;

6. The same variable name may be used more than once
public static void main(String[] args) {
int result = square(3) + square(4);
System.out.println(result); }
public static int square(int n)
int result = n * n;
return result;

7. You can have two variables with the same name in the same method
public static void main(String[] args) {
int sum = 0;
for (int i=1; i<=10; i++)
sum = sum + i; }

8. Illegal: two variables with the same name have their scopes overlapped
public static int sumOfSquares(int n) {
int sum = 0;
for (int i=1; i<=n; i++)
int n = i+1;
sum = sum + n; }
return sum;

9. Exercise what is the scope of variable i defined in line 13?
public class Sample {
public static void main(String[] args)
int x = 4;
x = mystery(x+1);
System.out.println(s); }
public static int mystery(int x)
int s = 0;
for (int i=0; i<x; x++)
int x = i+1;
s = s + x;
return s;
what is the scope of variable i defined in line 13?
which is the scope of variable x defined in line 10?
there are two scope errors in the code. what are they?