### If-Then-Elif-Else

 `If Then (s) [Else statement(s)]``If Then``   [statement(s)]`` [Elif Then]``   [statement(s)]``...[Else]``   [statement(s)]``End If`Makes a decision regarding program flow based on the result returned by an expression.If the result of is nonzero (logical true), the Then statement(s) is executed.If the result of expression is zero (false), the Then statement(s) is ignored and the Else statement(s), if present, is executed.Elif statement, as its name suggests, is a combination of If and Else. Like Else, it extends an If statement to execute a different statement in case the original If expression evaluates to False. However, unlike Else, it will execute that alternative expression only if the Elif conditional expression evaluates to True.Otherwise, execution continues with the next executable statement.Example 1:`If N%<20 And N%>10 Then Print "OK": GoTo skip_error``    Print "N% IS OUT OF RANGE"``skip_error:``    Rem --- N% is in the range (10..20)`Example 2:`If x>0 Then Print "Positive" Else Print "Negative"`Example 3:`If x>0 Then``    Print "Positive"``ElIf x<0 Then ``    Print "Negative"``Else``    Print "Zero"``End If`Example 4:`' If A > 10, execute the three colon-separated statements in the order``' that they appear``If A > 10 Then A = A + 1 : B = B + A : C = C + B`Example 5:`' If A > 10, execute the three statements in the order``' that they appear``If A > 10 Then ``     A = A + 1``     B = B + A``     C = C + B``End If`Example 6:`Input n%``If n% mod 2 = 0 Then ``    Print n%; " is even"``Else``    Print n%; " is odd"``End If`Example 7:````' graph2.bas - This file is part of nuBASIC` `dx%``=``GetSWidth``()` `dy%``=``GetSHeight``()` `Randomize` `While` `1` `x1%``=``Rnd``(``1``)``*``dx%` `x2%``=``Rnd``(``1``)``*``dx%` `y1%``=``Rnd``(``1``)``*``dy%` `y2%``=``Rnd``(``1``)``*``dy%` `t%``=``Int``(``Rnd``(``1``)``*``6``)` `c%``=``Int``(``Rnd``(``1``)``*&``hffffff``)` `If` `t%``=``1` `Then` `Line` `x1%``,``y1%``,``x2%``,``y2%``,``c%` `Elif` `t%``=``2` `Then` `Rect` `x1%``,``y1%``,``x2%``,``y2%``,``c%` `Elif` `t%``=``3` `Then` `FillRect` `x1%``,``y1%``,``x2%``,``y2%``,``c%` `Elif` `t%``=``4` `Then` `Ellipse` `x1%``,``y1%``,``x2%``,``y2%``,``c%` `Else` `TextOut` `x1%``,``y1%``,` `"nuBASIC"``,``c%` `End` `if` `k\$``=``InKey\$``()` `If` `k\$``=``"q"` `Then` `End` `End` `While````