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C++ Code Formatting

Braces

Never omit braces with two exceptions:

// early return:
if (condition)
    return;

// early continue:
if (condition)
    continue;

Line Breaks

Always place braces on new lines:

if (condition)
{
    statements;
}
else
{
    statements;
}

If you’re using multiple inheritance, you should place all super classes after the first one one a new line:

class UFooBarComponent : public UActorComponent,
    public IFooInterface,
    public IBarInterface
{
    // ...
};

Break very long lines (more than 100-200 characters) wherever it makes sense. Indent the following lines of the same statement.

One of the most common cases for are log lines:

UE_CLOG(bShouldLogError, LogFooCategory, Error, TEXT("An error occured while reading the coding conventions! (Source Actor: %s) "
    "This can happen if you are reading too fast (current reading speed: %f)"),
    *SourceActor->GetName(), SourceActor->ReadingSpeed);

Indentation

• Indent using tabs (4 characters)
• Align text following non-tab characters (e.g. function parameters, comments) using spaces:

    // Optionally align function parameters to aid legibility
    MyFunction(FirstParam,        SecondParam, true,  "some string");
    MyFunction(FirstParamVariant, SecondParam, false, "some different string");
  

• Indent code by execution blocks
• Indent 2nd/3rd/.. line of statements with line-breaks, e.g.

    UE_CLOG(LogTemp, Log, TEXT("My log message with many parameters %s, %i, %s"),
        *StringParameter1, // next lines of statement indented by a single tab
        IntParameter, StringParaneter2);
    // continue without indent after statement
  

• Use the same indentation rules for C# and Python files inside an Unreal Project

Spaces within Statements

• Add a space between if/for and parentheses

    if (myCondition) // good
    if(myCondition)  // bad
  

• Don’t add a space between function name and parentheses

    MyFunction();  // good
    MyFunction (); // bad
  

• Spaces in type declarations:
  • Don’t add spaces between type name and * or &
  • Do add a space before and after const
  • Do add a space between type and variable name
  • Examples:

      // good
      FFoo* MyFoo;
      const FFoo* MyFoo;
      FFoo* const MyFoo;
      FFoo const * const MyFoo;
    
      // bad
      FFoo * MyFoo;
      FFoo*MyFoo;
      FFoo*const MyFoo;
      FFoo const*const MyFoo;
    

Switch Statements

• each case must end with one of the following:
  • return;
  • break;
  • // falls through
• cases with multiple lines must be surrounded by braces
• always include a default case

Empty lines

• Leave at most two empty lines between declarations
• Always add an empty line at the bottom of a file to avoid parsing errors with some compilers such as gcc