National Instruments 320682C

Formatting and I/O Library Chapter 2

LabWindows/CVI Standard Libraries 2-36 © National Instruments Corporation

the integer is converted to a string format. You can enter any non-negative value

here. If n is less than the number of digits required to represent the integer, an

asterisk (*) will be inserted into the string to signify an overflow. The default for

n is zero, which indicates that the integer can occupy whatever space is necessary.

pc Specify Padding. The p integer modifier specifies a padding character c, which

fills the space to the left of an integer in the event it does not require the entire

width specified with the w

modifier. The default padding character is a blank.

sSpecify as Two’s Complement. The s integer modifier indicates that the integer

argument is considered a signed two's complement number. This is the default

interpretation of integers, so the s modifier is never explicitly required.

uSpecify as Unsigned. The u integer modifier indicates that the integer is

considered an unsigned integer.

onnnn Specify Byte Ordering. The o integer modifier is used to describe the byte

ordering of raw data so that LabWindows/CVI can map it to the byte order

appropriate for the Intel (PC) or Motorola (SPARCstation) architecture. The

number of

's must be equal to the byte size of the integer argument as specified

by the b

modifier, which must precede the o modifier. In the case of a four-byte

integer, o0123 indicates that the bytes are in ascending order of precedence (Intel

style), and o3210 indicates that the bytes are in descending order of precedence

(Motorola style).

In a Fmt function, the buffer containing the raw instrument data should have the

o modifier describing the byte ordering. The buffer without the o modifier is

guaranteed to be in the mode of the host processor. In other words,

LabWindows/CVI will reverse the byte ordering of the buffer without the

o modifier depending on which architecture the program is running on.

For example, if your GPIB instrument sends two-byte binary data in Intel byte

order, your code should appear as follows:

short int instr_buf[100];

short int prog_buf[100];

status = ibrd (ud, instr_buf, 200);

Fmt (prog_buf, "%100d<%100d[b2o01]", instr_buf);

If, instead, your GPIB instrument sends two-byte binary data in Motorola byte

order, the Fmt function should appear as follows:

Fmt (prog_buf, "%100d<%100d[b2o10]", prog_buf);

In either case, the o modifier is used only on the buffer containing the raw data

from the instrument (instr_buf). LabWindows/CVI will ensure that the

program buffer (prog_buf) is in the proper byte order for the host processor.