Creating Expressions and Statements 814
The expression in the parentheses can be any expression, but it usually contains one of
the relational expressions. If the expression has the value false, the statement is skipped.
If it evaluates true, the statement is executed. Consider the following example:
if (bigNumber > smallNumber)
bigNumber = smallNumber;
This code compares bigNumberand smallNumber. If bigNumberis larger, the second line
sets its value to the value of smallNumber. If bigNumberis not larger than smallNumber,
the statement is skipped.
Because a block of statements surrounded by braces is equivalent to a single statement,
the branch can be quite large and powerful:
if (expression)
{
statement1;
statement2;
statement3;
}
Here’s a simple example of this usage:
if (bigNumber > smallNumber)
{
bigNumber = smallNumber;
std::cout << “bigNumber: “ << bigNumber << “\n”;
std::cout << “smallNumber: “ << smallNumber << “\n”;
}
This time, if bigNumberis larger than smallNumber, not only is it set to the value of
smallNumber, but an informational message is printed. Listing 4.4 shows a more detailed
example of branching based on relational operators.LISTING4.4 A Demonstration of Branching Based on Relational Operators
1: // Listing 4.4 - demonstrates if statement
2: // used with relational operators
3: #include <iostream>
4: int main()
5: {
6: using std::cout;
7: using std::cin;
8:
9: int MetsScore, YankeesScore;
10: cout << “Enter the score for the Mets: “;
11: cin >> MetsScore;
12:
13: cout << “\nEnter the score for the Yankees: “;