X++ Programming Fundamentals Training November 2025

Dynamics Edge has your X++ Programming Fundamentals Training covered for November 2025 and beyond when you want to leverage the object oriented application aware and data aware x plus plus language for Dynamics 365 Finance and Operations for Development and what it can do for you.

Explore such key foundational concepts like object-oriented design, your loops, control flow, and more as you get a good explain on how X++ relates to concepts in other languages such as even pre- and post-increment operations from C++/C# to help bridge understanding on what is x++ versus ++X the pre increment operator versus post increment operator and how this is important in how the return value of the variable is affected in not only the C# C++ language but even the X++ programming language itself as well.

With our knowledge emphasizing its use in Dynamics 365 Finance and Operations, know the X++ syntax basics, distinguishing between preincrement and postincrement operations and much more. Go far beyond X++ language documentation of Microsoft Learn and get the advantage of a Dynamics Edge Virtual ILT or Instructor Led Training format. X++ as an object-oriented, application-aware language in ERP and db. It includes your system classes, SQL integration, best practices, and .NET interop for efficient performance.

Check out the nuances of X++: loop counter declaration, increment operator use, and unique syntax, to get clarity for you learners some of who might be transitioning from C#. Know the structure of X++ for beginners, including SQL-like statements, loop structures, and increment differences.  If you are looking into alternatives for just AX Developer Tips for Newbies you find on Google, Dynamics Edge’s Dynamics 365 X++ training April 2023 and newer or X++ Training April 2025 and further or better yet November 2025 or newer may be the right place for you.

X++ is an object-oriented programming language designed specifically for Microsoft’s enterprise resource planning (ERP) system, Dynamics 365 Finance & Operations (formerly Dynamics AX). It is a data-aware and application-aware language – meaning it integrates closely with the ERP’s data model and business logic. X++ syntax and concepts will feel familiar to developers with experience in C# or Java, but it also has unique features tailored to business application development. This overview will guide beginners through X++ basics, highlighting core language features, control structures like loops, and important concepts such as the difference between pre-increment and post-increment operators. Throughout, we’ll also touch on how X++ handles database access (for example, using the select statement) to retrieve and manipulate data.

The Basics of X++ and Its Role in Dynamics 365 FO

What is X++? In Dynamics 365 Finance & Operations, X++ is the primary language used for development and customization. It evolved from earlier versions of Dynamics AX and is now compiled to .NET Common Intermediate Language (CIL) for execution. This means X++ runs on the same runtime as C# and other .NET languages, giving it performance improvements and interoperability with .NET libraries. X++ code is typically written and executed within the Finance & Operations application environment (using Visual Studio as the development IDE in modern versions).

Object-Oriented and Familiar Syntax: X++ is an object-oriented language, supporting classes, inheritance, polymorphism, and other OOP principles. Syntactically, it resembles languages like C# and C++ in many ways. For example, it uses semicolon-terminated statements, curly braces for blocks, and // for single-line comments just as C#/C++ do. Basic control structures (if-else, switch, loops) are available in X++ and generally work similarly to those in C#. This familiarity helps C-family language developers get up to speed quickly with X++. However, there are some differences and restrictions in X++ that beginners should note, which we’ll explore below.

Best Practices and Environment: X++ development in Dynamics 365 comes with some built-in best practice checks. The compiler will flag certain patterns as best practice violations to guide developers in writing efficient, maintainable code. Also, since X++ runs inside the ERP environment, output and debugging are a bit different: rather than writing to a console, X++ uses the Infolog (a message window in the application) to show output or errors. For example, Global::info(“Hello”) or info(“Hello”) (a shorthand) will post an information message to the Infolog. This is analogous to Console.WriteLine in a standalone C# program, but tailored to the Dynamics environment.

Key Language Features and Syntax

Variables and Types: X++ supports a range of data types, including primitive types (integers, reals, strings, dates, etc.) and complex types like containers and classes. One small difference from languages like C#: X++ does not have a distinct char type – a single character is just a str (string) of length one. String literals can be written with either double quotes or single quotes in X++ (both are accepted). For instance, “Hello” and ‘Hello’ represent the same string in X++, which can be convenient if your string itself contains quotation marks. (By convention, developers typically use double quotes for user-facing strings in X++.)

Conditional Statements: All the usual conditional structures are present. The if and if…else statements in X++ work like those in C# with one noteworthy distinction: X++ is a bit more permissive in what can be treated as a boolean condition. In X++, any expression can be evaluated in an if – for example, an integer is false if it’s 0 and true otherwise, and an object is false if null and true if not null. This is more like C/C++ behavior, whereas C# requires a strictly boolean condition. Apart from that, writing conditional logic is straightforward, and X++ also provides a switch statement for multi-branch selection, and even a ternary ?: operator for inline conditional expressions.

Example – Simple Condition in X++:


int qty = 0;
;
if (qty) // In X++, 0 is interpreted as false
{
info("Quantity is nonzero");
}
else
{
info("Quantity is zero");
}


In the above snippet, the if (qty) will be false because qty is 0. In C#, this code wouldn’t compile (since qty isn’t a boolean), but X++ allows it, treating 0 as false.

Loops in X++: for, while, and do…while

Like most programming languages, X++ offers several looping constructs to repeat actions. The three types of loops available are for, while, and do…while loops. These work similarly to their counterparts in C# or Java, with a couple of X++-specific considerations.

While Loops: A while loop in X++ has the form while (condition) { … } and repeats as long as the condition remains true. This is identical in behavior to other languages’ while loops. For example:


int count = 1;
while (count <= 5)
{
info(strFmt("Count is %1", count));
count++;
}


This will iterate and print “Count is 1”, “Count is 2”, up to “Count is 5,” each time incrementing the counter. The while loop checks the condition first; if it’s true, the loop body executes, then the condition is checked again.

Do…while Loops: X++ also supports do…while, which ensures the loop body runs at least once before the condition is checked. The syntax is do { … } while (condition);. You might use a do-while when an action should happen at least one time (for example, prompting a user until they enter valid data, where you want to process the first attempt regardless). In practice, do-while is less common but good to know it exists and works just like in C/C++.

For Loops: The for loop in X++ uses the syntax for (initialization; test; increment) { … }. It behaves like the C-style for loop, running the initialization once, then looping as long as the test condition is true, and executing the increment step at the end of each iteration. A simple example:

int i;
for (i = 1; i <= 5; i++)
{
info(strFmt("i is %1", i));
}

This loop will execute 5 times (with i from 1 through 5). One peculiarity historically known in X++ is that you could not declare the loop counter variable inside the for-loop statement (unlike in C#). In older X++ versions, the int i had to be declared before the for loop, as shown above. Modern Dynamics 365 X++ might have relaxed this (and Microsoft’s docs show an example with for (int i = 0; …)), but if you encounter a compiler error, simply declare the counter outside the loop. This is a minor syntactic difference to be aware of if you’re coming from C#.

Loop Control: Inside any loop, you can use continue to skip to the next iteration or break to exit the loop early. These work the same as in C#/Java. For instance, you might use continue to skip processing certain items and break to stop entirely when some condition is met. Using these judiciously can help control loop flow and exit conditions.

Understanding the ++X vs X++ Increment Operators

One fundamental concept in many C-style languages is the difference between the pre-increment and post-increment operators – written as ++x and x++ respectively. X++ supports these increment operators, but with some restrictions and important behaviors to note.

General Difference: In any language that has them, ++x (pre-increment) means “increment x before using its value,” whereas x++ (post-increment) means “use x’s current value, then increment x.” For example, if x is 5, then int y = ++x; will set y to 6 (x becomes 6 first, then assigned to y). In contrast, x = 5; int y = x++; will set y to 5 and then increment x to 6 – so afterward x is 6, but y got the original value. The outcome differs because of when the increment operation occurs. This distinction might seem subtle, but it becomes important when these operators are used within larger expressions or assignments.

Using ++ in X++: In X++, you can certainly use the increment operators, but only as standalone statements – not embedded inside other expressions. In other words, you can do i++; or ++i; on a line by itself to add one to i. However, you cannot directly use an increment within, say, an assignment or method call. For instance, X++ would not compile code like print i++; because that tries to use the value of i++ in an expression (here as an argument to print). Similarly, something like j = i++; is not allowed in X++ (whereas it’s valid in C#). Microsoft’s documentation explicitly notes that an integer variable “decorated” with ++ can only be used as a statement by itself in X++. If you need to do an increment and use the value, you must split it into two steps in X++:

int j, i = 42;
i++;        // increment i (post-increment style, but standalone)
j = i;      // now use the incremented value

The above approach ensures clarity and compliance with X++ rules. You could also choose to do ++i; j = i; – in this simple context it’s the same result (j becomes 43 if i started at 42). The key is that the increment isn’t used within a larger expression.

Why It Matters: Understanding pre- vs post-increment is still important for X++ learners, even though X++ restricts their usage in expressions. First, if you read X++ code, you might see both i++ and ++i used. When used as standalone statements, i++ and ++i will both end up incrementing the variable by 1. In that specific context (not part of a bigger expression), there is no practical difference in the final outcome – i gets incremented either way. However, as a matter of style or micro-optimization, some developers prefer pre-increment (++i) since in some languages it avoids a temporary copy of the old value. In modern compiled code the difference is negligible, but you might still see both forms.

More importantly, if you ever transition between X++ and another language like C#, C++, or Java, you must remember that in those languages ++i and i++ can yield different results when used inside expressions. For example, in C# one might write y = i++ + 10; versus y = ++i + 10; and get different outcomes. In X++, you would have to do that in two lines, but conceptually knowing the difference protects you from logical errors. In summary, ++x increments first and x++ increments afterward, a principle that holds true broadly. X++ simply ensures you apply this principle in clearer, separate steps.

Data Access in X++: The Select Statement

One of X++’s powerful features (and a reason it’s called “data-aware”) is its built-in support for database operations using SQL-like syntax. In Dynamics 365 FO, the business data (customers, orders, transactions, etc.) is stored in a relational database. X++ provides keywords (very similar to SQL) to interact with this data directly from code.

The select Keyword: In X++, you can write a select statement to fetch records from a database table into a record buffer (an object that represents a table record). For example, suppose there is a table CustTable that holds customer accounts. You can retrieve a customer record like this:

CustTable cust;
select firstonly cust
where cust.AccountNum == ‘US-001’;

This X++ snippet will query the CustTable for a record where the AccountNum field equals “US-001”. The result is stored into the cust variable. The keyword firstonly is used here to indicate we only want the first matching record (if any). If a record is found, the cust buffer now holds that record’s data, and you could access fields like cust.Name, etc. If no matching record, cust would be essentially empty (its primary key, like cust.RecId, would be 0).

Retrieving Multiple Records: If you expect multiple records and want to iterate through them, you can use a while select loop. For example:

CustTable cust;
while select cust where cust.City == “Denver”
{
info(strFmt(“Customer %1 – %2”, cust.AccountNum, cust.Name));
}

This will go through all customers in Denver, one by one, and print their account number and name. The while select construct in X++ conveniently combines record fetching with looping – under the hood it fetches the next record each time the loop iterates.

SQL-like Syntax Details: X++ select statements support a lot of SQL features: you can join multiple tables, use aggregate functions, etc., though with some limitations. Notably, X++ requires that you select into a table buffer (i.e., an instance of a table). You can specify a field list to only fetch specific fields (for performance) – if you do, only those fields will be populated in the buffer, and others will be left null/uninitialized. For instance, select accountNum from cust where … will fetch only the AccountNum field; if you later try to use cust.Name it would not be set in that scenario. So you either select the fields you truly need or select the whole record (by just naming the buffer without a field list).

Another important feature is that X++ enforces transactions easily. If you update data, you typically enclose modifications in a transaction scope (ttsBegin/ttsCommit pairs). But for simply reading data with select, you don’t need explicit transaction handling – X++ will handle the database calls for you and you can trust the data is consistent as of when it was read. Keep in mind that large queries might time out if they run too long; the system throws an exception if a SQL query times out, which you can catch (the default timeout in an interactive session is 30 minutes, much shorter for batch sessions). However, for most day-to-day queries that fetch a reasonable number of records using indexed fields, you won’t hit those limits.

Example – Using Data from a Select: Building on the earlier example, after a select you can use the data:


CustTable cust;
select cust where cust.AccountNum == 'US-001';

if (cust.RecId != 0) // RecId is nonzero if a record was found
{
info(strFmt(“Customer %1 is named %2”, cust.AccountNum, cust.Name));
}
else
{
warning(“Customer US-001 not found.”);
}

Here we check cust.RecId (a system field that acts as the primary key) to determine if the select actually found a record. If not, the buffer remains empty (RecId == 0). If yes, we can safely use other fields like Name. This pattern is common in X++ when using select without firstonly inside an if – essentially treating it as “select first match or nothing.”

Putting It All Together

For a beginner to X++, the language offers a comfortable blend of familiar programming constructs and specialized features for business applications. You’ve seen how loops in X++ allow repetitive tasks just like in other languages, with minor syntax differences in for loops and the availability of do…while. We discussed the increment operators and clarified the conceptual difference between ++x and x++, noting that X++ restricts using these inside larger expressions for clarity. And importantly, we explored the integrated SQL-like capabilities of X++: the select statement and related constructs that let you query and manipulate database records easily from your code.

X++’s tight integration with the Dynamics 365 FO platform means that as you write code, you are often directly working with high-level business objects (like tables representing customers, orders, etc.) and you benefit from built-in safeguards and conventions of the environment (such as compile-time checks and the Infolog for output).

Next Steps: With this understanding, beginners should practice writing simple X++ jobs or classes: try creating loops, using conditional logic, and querying some sample tables. Pay attention to the nuances – for instance, ensure you don’t try to use i++ in a complex expression in X++, and remember to handle data retrieval results properly. The more you work in X++, the more you’ll appreciate its blend of general-purpose language features with ERP-specific power. Happy coding in X++!