National Instruments 320682C

Chapter 2 Formatting and I/O Library

than the number of bytes available from the source, the remaining bytes are filled

with ASCII NULs if the q modifier is used or blanks if the q modifier is not present.

When the w modifier is used in conjunction with the a modifier,

indicates the

number of bytes to append to the string excluding the terminating ASCII NUL.

If wn modifies a target string and

is larger than the number of bytes in the target

argument, the target argument is overwritten in compiled C.

qAppend NULs. When applied to a target string in conjunction with the w string

modifier, the q string modifier specifies that unfilled bytes at the end of the target

string be set to ASCII NULs instead of blanks.

yAppend with Spacing. When the source is a string and the y modifier is applied to a

target string format specifier, the target string is filled with bytes from the source

string without skipping leading spaces or tabs.

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

When applied to a target string that is being filled from a source string, the t modifier

specifies that filling of the target is terminated on the first occurrence of the character

, where

is the ASCII value of the character. Thus, %s[t59] causes reading of

the source string to stop on an ASCII semicolon. More than one t modifier can occur

in the same specifier, in which case filling of the target terminates when any of the

terminators occur. If no t modifier is present, filling of the target stops on any

whitespace character.

t- Terminate when Full. This is similar to t

, except that it specifies that there are no

terminating characters. When applied to a source string, t- specifies that reading of

the source string terminates when all of the targets are full or when the number of

bytes specified with the w modifier have been read. When applied to a target string,

t- specifies that filling of the target string terminates when the source is exhausted or

when the number of bytes specified with the w modifier have been placed into the

target.

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

ASCII values of the characters +, -, and 0 through 9. When applied to a source

(target), it specifies that reading of the source string (filling of the target string) be

terminated upon occurrence of a numeric expression. Using %s>%s[t#]%d with the

source string ab567, ab is placed in the first target and the integer 567 is placed in

the second target.