National Instruments 320682C

Chapter 2 Formatting and I/O Library

tn Terminate on Character. When applied to a source string, the t string modifier

specifies that the source string is terminated on the first occurrence of the character

where

is the ASCII value of the character. Thus, %s[t44] causes reading of the

source string to stop on an ASCII comma. Using %s[t44] and the source string

Hello, World! as an example, Hello is placed into the target. More than one

t modifier can occur in the same specifier, in which case the string terminates when

any of the terminators occur. If no t modifier is present, reading of the source string

stops on an ASCII NUL. This modifier has no effect when applied to the target

specifier.

t- Terminate when Full. This is similar to t

, except that it specifies that there are no

terminating characters. Reading of the source string terminates when the target is full

or when the number of bytes specified with the w modifier have been read.

t# Terminate on Number. This is equivalent to repeating the t modifier with the

ASCII values of the characters +, -, and 0 through 9. It specifies that reading of the

source string be terminated upon occurrence of a numeric expression. Using %s[t#]

with the source string ab567, ab is placed in the target.

Fmt, FmtFile, FmtOut—Asterisks (*) Instead of Constants in Format Specifiers

Often, one or more integer values are required in a format specifier. The format specifier for an

integer array, for example, requires the number of elements (rep). You can use constants for

these integer values in format specifiers. Alternatively, you can specify an integer value using an

argument in the argument list. When you use this method, substitute an asterisk (*) for the

constant in the format specifier.

You can use the asterisk in the following format specifier elements:

rep For integer or floating-point arrays

in For integer or floating-point arrays, or strings

wn For any format specifier

pn For floating-point specifiers only

en For floating-point specifiers only

rn For integer specifiers only

When you use one or more asterisks instead of constants in a target specifier, the arguments

corresponding to the asterisks must appear after the format string in the same order as their

corresponding asterisks appear in the format specifier.

When you use one or more asterisks instead of constants in a source specifier, the arguments

corresponding to the asterisks must precede the source argument and must be in the same order

as their corresponding asterisks in the format specifier.