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ANSI C Library Chapter 1
LabWindows/CVI Standard Libraries 1-6 © National Instruments Corporation
Input/Output Facilities
The function rename fails if the target file already exists. Under Microsoft Windows, rename
fails if the source and target files are on different disk drives. Under UNIX, rename fails if the
source and target files are on different file systems.
The functions fgetpos and ftell set errno to EFILPOS on error.
errno Set by File I/O Functions
The errno global variable is set to indicate specific error conditions by the ANSI C file I/O
functions and the low-level I/O functions. The possible values of errno are declared in
cvi\include\ansi\errno.h. There is a base set of values that is common to all
platforms. There are additional values that are specific to particular platforms.
Under Windows 3.1, errno gives very limited information. If the operating system returns an
error, errno is set to EIO.
Under Windows 95 and NT, you can call the Windows SDK GetLastError function to
obtain system specific information when errno is set to one of the following values:
EACCES
EBADF
EIO
ENOENT
ENOSPC
Mathematical Functions
The macro HUGE_VAL defined in the header math.h as well as the macros FLT_EPSILON,
FLT_MAX, FLT_MIN, DBL_EPSILON, DBL_MAX, DBL_MIN, LDBL_EPSILON, LDBL_MAX,
and DBL_MIN defined in the header float.h all refer to variables. Consequently, these
macros cannot be used in places where constant expressions are required, such as in global
initializations.
Time and Date Functions
Function time returns the number of seconds since January 1, 1990.
Functions mktime and localtime require time zone information to produce correct results.
LabWindows/CVI obtains time zone information from the environment variable named TZ, if it
exists. The value of this variable should have the format AAA[S]HH[:MM]BBB, where optional
items are in square brackets.