# Subgoals

## Section4.10Worked Example: Nested If Statements

### Subgoals for Evaluating Selection Statements.

1. Diagram which statements go together
2. For if statement, determine whether expression is true or false
3. If true ߝ follow true branch, if false ߝ follow else branch or do nothing if no else branch

### Subsection4.10.1

You can watch this video or read through the content below it.
Given the following declarations:
int alpha = 2, beta = 1, delta = 3, eta = 0, gamma = 0;

double omega = 2.5, theta = -1.3, kappa = 3.0, lambda = 0.0, rho = 0.0;

Evaluate these statements and determine the value of all variables used.
if (omega < kappa)
{
if (alpha < delta)
eta = 5;
if (alpha < eta)
gamma = 4;
}
rho = -1.0;


### Subsection4.10.2SG1: Diagram which statements go together.

In this diagram, the first thing to note is the parent/outer if-statement highlighted in blue.
Inside the true branch of the parent/outer if-statement, there are two sequential if-statements.
The final single statement is highlighted in green, and it is not part of the nested if-statements, so it will always be executed.

### Subsection4.10.3SG2: For if statement, determine whether true or false

Because there are 2 sequential if-statements, we start with the first one, and then repeat SG2 and SG3 for the other.
First we evaluate (omega < kappa):
(2.5 < 3.0) is TRUE

### Subsection4.10.4SG3: If true, follow true branch. If false, follow else branch (OR do nothing if there is no else branch).

The true branch contains two sequential if-statements, so we must repeat the SG2 and SG3 for each of them.

### Subsection4.10.5SG2: For if statement, determine whether true or false

First we evaluate (alpha < delta):
(2 < 3) is TRUE

### Subsection4.10.6SG3: If true, follow true branch. If false, follow else branch (OR do nothing if there is no else branch).

The condition is TRUE so we follow the true branch.
eta = 5;

### Subsection4.10.7SG2: For if statement, determine whether true or false

Now we do the second if-statement in the inner sequence.
First we evaluate (alpha < eta):
(2 < 5) is TRUE

### Subsection4.10.8SG3: If true, follow true branch. If false, follow else branch (OR do nothing if there is no else branch).

The condition is TRUE so we follow the true branch.
gamma = 4;
Next, the final sequential statement after the entire selection structure is always executed:
rho = -1.0;
Hint.
Answer: omega = 2.5, kappa = 3.0, alpha = 2, delta = 3, eta = 5, gamma = 4, rho = -1.0