iface

Specifies the default calling convention for an application or the argument-passing convention used for hidden-length character arguments.

IDE Equivalent

Windows:
External Procedures > Calling Convention (/iface:{cref|stdref|stdcall|cvf|default}
External Procedures > String Length Argument Passing (/iface:[no]mixed_str_len_arg)
Linux: None
Mac OS: None

Architectures

IA-32 architecture, Intel® 64 architecture, IA-64 architecture

Syntax

Linux and Mac OS:	None
Windows:	/iface:keyword

Arguments

keyword	Specifies the calling convention or the argument-passing convention. Possible values are:
	default	Tells the compiler to use the default calling conventions.
	cref	Tells the compiler to use calling conventions C, REFERENCE.
	cvf	Tells the compiler to use calling convention CVF.
	[no]mixed_str_len_arg	Determines the argument-passing convention for hidden-length character arguments.
	stdcall	Tells the compiler to use calling convention STDCALL.
	stdref	Tells the compiler to use calling conventions STDCALL, REFERENCE.

Default

/iface:default	The default calling convention is used.
/iface:nomixed_str_len_arg	Hidden lengths are placed in sequential order at the end of the argument list.

Description

This option specifies the default calling convention for an application or the argument-passing convention used for hidden-length character arguments.

On systems using IA-32 architecture, you can change the default calling convention by using one of the following methods:

Specify /iface:cref, /iface:cvf, /iface:stdcall, or /iface:stdref
Specify the ATTRIBUTES directive (using the C, STDCALL, REFERENCE, or VALUE option) in an explicit interface

The second method overrides the first.

On systems using Intel® 64 architecture, you cannot change the default calling convention because only one calling convention exists on those systems.

On On systems using IA-64 architecture, the only option available is /iface:default.

Option	Description
/iface:default	Tells the compiler to use the default calling conventions. This is the only option available on systems using IA-64 architecture.
/iface:cref	Tells the compiler to use calling conventions C, REFERENCE.
/iface:cvf	Tells the compiler to use calling convention CVF (Compaq* and Powerstation* compatibility). By default, /iface:cvf passes arguments by reference. /iface:cvf sets the /iface:mixed_str_len_arg option. This causes CHARACTER variables to be passed as address/length pairs.
/iface:mixed_str_len_arg	Specifies argument-passing conventions for hidden-length character arguments. This option tells the compiler that the hidden length passed for a character argument is to be placed immediately after its corresponding character argument in the argument list. This is the method used by Microsoft* Fortran PowerStation. When porting mixed-language programs that pass character arguments, either this option must be specified correctly or the order of hidden length arguments changed in the source code.
/iface:stdcall	Tells the compiler to use calling convention STDCALL. By default, /iface:stdcall passes arguments by value.
/iface:stdref	Tells the compiler to use calling conventions STDCALL, REFERENCE.

The /iface:stdcall and /iface:cvf options cause the routine compiled and routines that are called to have a @<n> appended to the external symbol name, where n is the number of bytes of all parameters. Both options assume that any routine called from a Fortran routine compiled this way will do its own stack cleanup.

On systems using Intel® 64 architecture, using /iface:stdcall does not change the naming convention.

Caution

On Windows systems, if you specify option /iface:cref, it overrides the default for external names and causes them to be lowercase. It is as if you specified "!dec$ attributes c, reference" for the external name.
If you specify option /iface:cref and want external names to be uppercase, you must explicitly specify option /names:uppercase.

Alternate Options

/iface:cvf	Linux and Mac OS: None Windows: /Gm
/iface:mixed_str_len_arg	Linux and Mac OS: -mixed-str-len-arg Windows: None
/iface:nomixed_str_len_arg	Linux and Mac OS: -nomixed-str-len-arg Windows: None
/iface:stdcall	Linux and Mac OS: None Windows: /Gz