Chapter 1 LabWindows/CVI Compiler
LabWindows/CVI Programmer Reference Manual 1-6
©
National Instruments Corporation
C Data Types and 32-Bit Compiler Issues
This section introduces the LabWindows/CVI compiler data types and discusses converting
16-bit source code to 32-bit source code.

Data Types

Table1-2 shows the LabWindows/CVI allowable data types.
The size of an enumeration type depends on the value of its enumeration constant.
InLabWindows/CVI, characters are signed, unless you explicitly declare them unsigned.
The types float and double conform to 4-byte and 8-byte IEEE standard formats.

Converting 16-Bit Source Code to 32-Bit Source Code

If you convert a LabWindows for DOS application to a LabWindows/CVI application, use
this section as a guide after you complete the steps in Chapter 12, Converting LabWindows
for DOS Applications, of the Getting Started with LabWindows/CVI manual.
In general, if you make few assumptions about the sizes of data types, little difference exists
between a 16-bit compiler and a 32-bit compiler except for the larger capacity of integers and
the larger address space for arrays and pointers.
Table 1-2. LabWindows/CVI Allowable Data Types
Type Size Minimum Maximum
char 8 –128 127
unsigned char 8 0 255
short 16 –32,768 32,767
unsigned short 16 0 65,535
int; long int 32 –231 231–1
unsigned int 32 0 232–1
unsigned long 32 0 232–1
float 32 –3.40282E+38 3.40282E+38
double; long double 64 –1.79769E+308 1.79769E+308
pointers (void *)32 N/A N/A
enum 8, 16, or 32 –231 231 –1

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