PeopleCode expression

This section mainly elaborates from the following parts

• Base expression
• Constant
• Function expression
• System variables
• Metastring
• Defined name references
• Summary of reserved words

Base expression

The expression gives peoplecode Value of data type . A simple peoplecode An expression can consist of a constant , Temporary variable , System variables ,record References to fields , Or function call composition . Simple expressions can be modified by unary operators （ For example, negative sign or logical non ）, Or use binary operators to combine into mixed expressions （ For example, plus sign or logical and ）.

The string obtained by defining the name reference is in PTtools Defined in the . for example record or page. They can make you refer to definitions rather than text strings , Because it will be difficult to maintain .

Constant

peoplecode Support digital type , String and Boolean constants , It also supports our custom constants . Constants are also supported NULL, It points to an invalid object reference .

notes ： We can express the date by converting string and numeric constants , Date time and time . Use Date,Date3,DateTime6,DateTimeValue,DateValue,Time3,TimePart and TimeValue Function to achieve the purpose . We can also use FormatDateTime To format the date value in text format .

Digital constant

The number constant is any number in decimal . for example ：

• 7
• 0.888
• -123.0023

String constant

String constants can be defined by either single quotation marks or double quotation marks . If a quotation mark is part of a string , Then we need to use another kind of quotation mark as the definition of string constant ,. As an alternative , We can include this delimiter twice . for example ：

• "This is a string constant."
  

• 'So is this.'
  

• 'She said, "This is a string constant."'
  

• "She said, ""This is a string constant."""
  

  Use the following code to include quotation marks in your string as text ：

  &cDblQuote = '"'; /* singlequote doublequote singlequote */
  

  The following example will produce a double quoted string ：

  &cDblQuote = """"; /* dquote dquote dquote dquote */
  

  We can also embed double quotation marks in the string twice ：

  &sImage = Char(10) | '<IMG SRC="%IMAGE(' | &pImageName | ')"';
  

  The string must be one line , If we need to create a multi line string , Then we must use the concatenation character to connect the strings into one line .

  &string = "Line 1" | Char(10) | "Line 2" | Char(10);
  

  Boolean value

  Boolean constant represents a truth value . It has two values , One is true, One is false.

  NULL Constant

  NULL A constant represents an object that does not point to a valid value . This means calling a method or trying to get or set a failed value .NULL Constant is its keyword NULL.

  User defined constant

  We can define constants at the beginning of the program . Then we can use the values associated with these declared constants anywhere . Constants can be defined as numbers , String type , Boolean type value .

  User defined constants can only be used in the following ways .

  • Constant &Start_New_Instance = True;

  • Constant &Display_Mode = 0;

  • Constant &AddMode = “A”:

  • Local Field &Start_Date;

  ...