User`s manual

Dynamic C User’s Manual digi.com 29
4.5.3 Macro Restrictions
The number of arguments in a macro call must match the number of parameters in the macro definition.
An empty parameter list is allowed, but the macro call must have an empty argument list. Macros are
restricted to 32 parameters and 126 nested calls. A macro or parameter name must conform to the same
requirements as any other C name. The C language does not perform macro replacement inside string liter-
als, character constants, comments, or within a #define directive.
A macro definition remains in effect unless removed by an #undef directive. If an attempt is made to
redefine a macro without using #undef, a warning will appear and the original definition will remain in
effect.
4.6 Numbers
Numbers are constant values and are formed from digits, possibly a decimal point, and possibly the letters
U, L, X, or A–F, or their lower case equivalents. A decimal point or the presence of the letter E or F
indicates that a number is real (has a floating-point representation).
Integers have several forms of representation. The normal decimal form is the most common.
10 –327 1000 0
An integer is long (32-bit) if its magnitude exceeds the 16-bit range (-32768 to +32767) or if it has the let-
ter L appended.
0L -32L 45000 32767L
An integer is unsigned if it has the letter U appended. It is long if it also has L appended or if its magni-
tude exceeds the 16-bit range.
0U 4294967294U 32767U 1700UL
An integer is hexadecimal if preceded by 0x.
0x7E 0xE000 0xFFFFFFFA
It may contain digits and the letters a–f or A–F.
An integer is octal if begins with zero and contains only the digits 0–7.
0177 020000 000000630
A real number can be expressed in a variety of ways.
4.5 means 4.5
4f means 4.0
0.3125 means 0.3125
456e-31 means 456 × 10
–31
0.3141592e1 means 3.141592