Use of Nested if-else statements:
By using the nested if-else to select from among the three possibilities, not all the conditions should be tested. In this situation, if x is less than -1, the statement is assign 1 to y is then executed, and the if-else statement is done so no other conditions are tested. If, though, x is not less than -1, then the else clause is executed. When the else clause is executed, then we know that x is greater than or equal to -1 so that section does not require to be tested. Rather than that, there are only two remaining possibilities: either x is less than or equal to 2, or it is bigger than 2. An if-else statement is used to select between those two possibilities. Therefore, the action of the else clause was the other if-else statement. Though it is long, this is one if-else statement, and a nested if-else statement. The actions are indented to represent the structure.
Nesting if-else statements in such a way that it can be used to select from among three, four, five, or more options-the possibilities are practically endless!
This is really an illustration of a particular type of nested if-else known as cascading if-else statement. In this category of nested if-else statement, the conditions and actions cascade in the stair-like pattern.