Evaluating an expression's truth value:
`true` or `false`.

Making a decision with `if( )`.

Extending `if( )` with `else`.

Extending `if( )` with `elseif( )`.

Putting multiple statements inside an `if( )`,
`elseif( )`, or `else` code block.

Using the equality (`= =`) and not-equals
(`!=`) operators in test expressions.

Distinguishing between assignment (`=`) and equality
comparison (`= =`).

Using the less-than (`<`), greater-than
(`>`), less-than-or-equal-to
(`<=`), and greater-than-or-equal-to
(`>=`) operators in test expressions.

Comparing two floating-point numbers with `abs( )`.

Comparing two strings with operators.

Comparing two strings with `strcmp( )` or
`strcasecmp( )`.

Using the negation operator (`!`) in test
expressions.

Using the logical operators (`&&` and
`||`) to build more complicated test expressions.

Repeating a code block with `while( )`.

Repeating a code block with `for( )`.