4.1.7.1 Initialization Expressions

An initialization expression must evaluate at compile time to a constant. It is used to specify an initial value for an entity.

In an initialization expression, each operation is intrinsic and each operand is one of the following:

• A constant or subobject of a constant
  
  
• An array constructor where each element and the bounds and strides of each implied-do, are expressions whose primaries are initialization expressions
  
  
• A structure constructor whose components are initialization expressions
  
  
• An elemental intrinsic function reference of type integer or character, whose arguments are initialization expressions of type integer or character
  
  
• A reference to one of the following inquiry functions:
  
  

  BIT_SIZE	MINEXPONENT
  DIGITS	PRECISION
  EPSILON	RADIX
  HUGE	RANGE
  ILEN	SHAPE
  KIND	SIZE
  LBOUND	TINY
  LEN	UBOUND
  MAXEXPONENT

  Each function argument must be one of the following:

  • An initialization expression
    
    
  • A variable whose kind type parameter and bounds are not assumed or defined by an ALLOCATE statement, pointer assignment, or an expression that is not an initialization expression
  
  
• A reference to one of the following transformational functions (each argument must be an initialization expression):
  
  

  REPEAT	SELECTED_REAL_KIND
  RESHAPE	TRANSFER
  SELECTED_INT_KIND	TRIM

  
  
• A reference to the transformational function NULL
  
  
• An implied-do variable within an array constructor where the bounds and strides of the corresponding implied-do are initialization expressions
  
  
• Another initialization expression enclosed in parentheses

Each subscript, section subscript, and substring starting and ending point must be an initialization expression.

In an initialization expression, the exponential operator (**) must have a power of type integer.

If an initialization expression invokes an inquiry function for a type parameter or an array bound of an object, the type parameter or array bound must be specified in a prior specification statement (or to the left of the inquiry function in the same statement).

Examples

The following examples show valid and invalid initialization (constant) expressions:

For More Information:

• On array constructors, see Section 3.4.2.4.
  
  
• On structure constructors, see Section 3.2.4.
  
  
• On intrinsic functions, see Chapter 9.