Cara menggunakan primary expression expected javascript

You should add using namepace LedDriver at the top of the LedDriverTest.cpp file.

The compilation error is caused by the fact your class LedDriver is declared in the namespace LedDriver, but you do not specify this and the compiler only looks for it in the default namespace during compilation of LedDriverTest.cpp. The using clause tells it to look in the namespace LedDriver as well as the default namespace when resolving names.

You could explicitly use the LedDriver:: prefix to specifically tell the compiler which namespace to look in if you prefer. However, given your usage - the testing of LedDriver - it is natural and easily readable if you you the using directive. The reason is the test file is closely associated with the tested functionality - so you're not making the code any less clear by omitting that namespace with every declaration. Also, it helps you remove the clutter of LedDriver:: used repeatedly and often within the file.

Primary Expressions

The simplest expressions, known as primary expressions, are those that stand alone—they do not include any simpler expressions. Primary expressions in JavaScript are constant or literal values, certain language keywords, and variable references.

Literals are constant values that are embedded directly in your program. They look like these:

1.23         // A number literal
"hello"      // A string literal
/pattern/    // A regular expression literal

JavaScript syntax for number literals was covered in Numbers. String literals were documented in Text. The regular expression literal syntax was introduced in Pattern Matching and will be documented in detail in Chapter 10.

Some of JavaScript’s reserved words are primary expressions:

true      // Evalutes to the boolean true value
false     // Evaluates to the boolean false value
null      // Evaluates to the null value
this      // Evaluates to the "current" object

We learned about true, false, and null in Boolean Values and null and undefined. Unlike the other keywords, this is not a constant—it evaluates to different values in different places in the program. The this keyword is used in object-oriented programming. Within the body of a method, this evaluates to the object on which the method was invoked. See Invocation Expressions, Chapter 8 (especially Method Invocation), and Chapter 9 for more on this.

Finally, the third type of primary expression is the bare variable reference:

i             // Evaluates to the value of the variable i.
sum           // Evaluates to the value of the variable sum.
undefined     // undefined is a global variable, not a keyword like null.

When any identifier appears by itself in a program, JavaScript assumes it is a variable and looks up its value. If no variable with that name exists, an attempt to evaluate a nonexistent variable throws a ReferenceError instead.

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Example

Delete 3 characters from a string, starting in position 1, and then insert "HTML" in position 1:

SELECT STUFF('SQL Tutorial', 1, 3, 'HTML');

Try it Yourself »


Definition and Usage

The STUFF() function deletes a part of a string and then inserts another part into the string, starting at a specified position.

Tip: Also look at the REPLACE() function.

Syntax

STUFF(string, start, length, new_string)

Parameter Values

ParameterDescription
string Required. The string to be modified
start Required. The position in string to start to delete some characters
length Required. The number of characters to delete from string
new_string Required. The new string to insert into string at the start position

Technical Details

Works in:SQL Server (starting with 2008), Azure SQL Database, Azure SQL Data Warehouse, Parallel Data Warehouse

More Examples

Example

Delete 1 character from a string, starting in position 13, and then insert " is fun!" in position 13:

SELECT STUFF('SQL Tutorial!', 13, 1, ' is fun!');

Try it Yourself »