X++ conditional statements

2025-05-19

This article describes the conditional statements in X++. The conditional statements are if, if...else, and switch. The ternary operator (?:) provides a value based on the provided expression. You use conditional statements to specify whether a statement is executed (with the if statement), or which is executed (with the if..else). Different conditional statements offer advantages in different situations.

if and if...else statements

The if statement evaluates a conditional expression, and then executes a statement if the conditional expression is evaluated as true. You can use the else clause to provide an alternative statement that's executed if the condition is evaluated as false. The syntax for an if...else statement is:

if ( expression ) statement [else statement ]

In this syntax, both occurrences of statement can be compound statements (zero or more statements enclosed in braces). The expression in the parentheses (that is, the conditional expression) can be any valid expression that is interpreted as true or false. Values of all types can be interpreted as boolean values: All numbers except 0 (zero) are true and all nonempty strings are true. You can nest if statements. However, if the nesting of if statements becomes too deep, you may consider using a switch statement instead to enhance legibility.

Examples of if and if...else statements

// if statement
if (a > 4)
{
   info("a is greater than 4");
}

// if... else statement 
if (a > 4)
{
   info("a is greater than 4");
}
else
{
   info("a is less than or equal to 4");
}

switch statements

The switch statement is a multibranch language construct that has the same behavior as nested if statements. The expression after the switch keyword is evaluated and checked against each case value. The case values must be constants so they can be evaluated at compile-time.

If a case constant matches the switch expression, the case statement is executed.
If the case contains a break statement, the program then jumps out of the switch.
If the case doesn't contain a break statement, the program continues and executes the next case statements.
If no matches are found, the default statement is executed.
If there are no matches and no default statement, none of the statements inside the switch statement are executed.

Here is the syntax for a switch statement:

switch ( expression ) { { case } [default: statement ] }

The syntax for a case block is:

case expression { , expression } : statement

In general, you should avoid situations where you don't use the break statement to exit each case, since it's easy to misread such code.

Examples of switch statements

When you include the break keyword in a switch statement, the execution of the case branch terminates, and the statement following the switch is executed. As shown in the following example, if the Debtor account number is 1000, the program executes "do something", and then continues execution after the switch statement.

switch (Debtor.AccountNo)
{
    case "1000":
        // do something
        break;
    case "2000":
        // do something else
        break;
    default:
        // default statement
        break;
}

The following code example makes the execution drop through the first case branch by omitting a break statement. If x is 10, b is assigned to a, and d is assigned to c. If x is 11, d is assigned to c. If x is 12, f is assigned to e.

 switch (x)
 {
     case 10:
         a = b;
     case 11:
         c = d;
         break;
     case 12:
         e = f;
         break;
 }

If you don't use the break statement, the program flow in the switch statement continues into the next case. Code segments A and B have the same behavior.

This flow isn't recommended.

// Code segment A (break omitted)
case 13:
case 17:
case 21:
case 500:
    info("g");
    break;

// Code segment B (the values are comma-delimited)
case 13, 17, 21, 500;
    info("g");
    break;

Ternary operator (?)

The ternary operator (?:) is a conditional expression that is resolved to one of two values. Here's the syntax for the ternary operator:

expression1 ? expression2 : expression3

In this syntax, expression1 is interpreted as a boolean value of true or false. If expression1 is true, the whole ternary statement returns expression2. Otherwise, the statement returns expression3. Both expression2 and expression3 must have the same type.

Examples of the ternary operator (?:)

The following code example returns one of two strings based on a Boolean return value from a method call. The Boolean expression indicates whether the CustTable table has a row with a RecId field value of 1. If this Boolean expression is true (meaning RecId != 0), found is assigned to result. Otherwise, the alternative not found is assigned to result.

result = (custTable::find("1").RecId) ? "found" : "not found";

You can nest expressions with the ternary operator. The following example assigns one of three values to level based on the value of x.

int x = 1001;
str level = x <= 1000 ? "A" : (x <= 2000 ? "B" : "C");
info(level);
// Output is "B".

Share via