Glossary C

carriage-control character: A character in the first position of a printed record that determines the vertical spacing of the output line.
character constant: A constant that is a string of printable ASCII characters enclosed by apostrophes (') or quotation marks (").
character expression: A character constant, variable, function value, or another constant expression, separated by a concatenation operator (//); for example, DAY// ' FIRST'.
character set: A mapping of characters to their identifying numeric values. See also multibyte character set.
character storage unit: The unit of storage for holding a scalar value of default character type (and character length one) that is not a pointer. One character storage unit corresponds to one byte of memory.
character string: A sequence of contiguous characters; a character data value. See also character constant.
character substring: One or more contiguous characters in a character string.
child process: A process (child) initiated by another process (the parent). The child process can operate independently from the parent process. Further, the parent process can suspend or terminate without affecting the child process. See also parent process.
child window: A window that has the WS_CHILD style. A child window always appears within the client area of its parent window. See also parent window.
column-major order: See order of subscript progression.
comment: Text that documents or explains a program. In free source form, a comment begins with an exclamation point (!), unless it appears in a Hollerith or character constant.

In fixed and tab source form, a comment begins with a letter C or an asterisk (*) in column 1. A comment can also begin with an exclamation point anywhere in a source line (except in a Hollerith or character constant) or in column 6 of a fixed-format line. The comment extends from the exclamation point to the end of the line.

The compiler does not process comments, but shows them in program listings. See also compiler directive.
common block: A physical storage area shared by one or more program units. This storage area is defined by a COMMON statement. If the common block is given a name, it is a named common block; if it is not given a name, it is a blank common.
compilation unit: The source file or files that are compiled together to form a single object file, possibly using interprocedural optimization across source files. Only one f90 command is used for each compilation, but one f90 command can specify that multiple compilation units be used.
compiler directive: A structured comment that tells the compiler to perform certain tasks when it compiles a source program unit. Compiler directives are usually compiler-specific. (Some Fortran compilers call these directives "metacommands".)
complex constant: A constant that is a pair of real or integer constants representing a complex number; the pair is separated by a comma and enclosed in parentheses. The first constant represents the real part of the number; the second constant represents the imaginary part.

The following types of complex constants are available on all systems: COMPLEX (COMPLEX(4)) and DOUBLE COMPLEX (COMPLEX(8)). On OpenVMS, Tru64 UNIX, and Linux systems, COMPLEX(16) is also available.
complex type: A data type that represents the values of complex numbers. The value is expressed as a complex constant. See also data type.
component: A part of a derived-type definition. There must be at least one component (intrinsic or derived type) in every derived-type definition.
concatenate: The combination of two items into one by placing one of the items after the other. In Fortran 95/90, the concatenation operator (//) is used to combine character items. See also character expression.
conformable: Pertains to dimensionality. Two arrays are conformable if they have the same shape. A scalar is conformable with any array.
console: An interface that provides input and output to character-mode applications.
constant: A data object whose value does not change during the execution of a program; the value is defined at the time of compilation. A constant can be named (using the PARAMETER attribute or statement) or unnamed. An unnamed constant is called a literal constant. The value of a constant can be numeric or logical, or it can be a character string. Contrast with variable.
constant expression: An expression whose value does not change during program execution.
construct: A block of statements, beginning with CASE, DO, IF, FORALL, or WHERE statement, and ending with the appropriate termination statement.
contiguous: Pertaining to entities that are adjacent (next to one another) without intervening blanks (spaces); for example, contiguous characters or contiguous areas of storage.
control character: A character string, usually with an ASCII value between 0 and 31, used to communicate with devices such as printers, modems, and the like.
control edit descriptor: A format descriptor that directly displays text or affects the conversions performed by subsequent data edit descriptors. Except for the slash descriptor, control edit descriptors are nonrepeatable.
control statement: A statement that alters the normal order of execution by transferring control to another part of a program unit or a subprogram. A control statement can be conditional (such as the IF construct or computed GO TO statement) or unconditional (such as the STOP or GO TO statement).
critical section: An object used to synchronize the threads of a single process. Only one thread at a time can own a critical-section object.