diff options
| -rw-r--r-- | devel.but | 11 | ||||
| -rw-r--r-- | puzzles.h | 3 |
2 files changed, 14 insertions, 0 deletions
@@ -4819,6 +4819,17 @@ returns the one which compares greater or less respectively. These macros may evaluate their arguments multiple times. Avoid side effects. +\S{utils-max-digits} \cw{MAX_DIGITS()} + +The \cw{MAX_DIGITS()} macro, defined in the main Puzzles header file, +takes a type (or a variable of that type) and expands to an integer +constant representing a reasonable upper bound on the number of +characters that a number of that type could expand to when formatted +as a decimal number using the \c{%u} or \c{%d} format of +\cw{printf()}. This is useful for allocating a fixed-size buffer +that's guaranteed to be big enough to \cw{sprintf()} a value into. +Don't forget to add one for the trailing \cw{'\\0'}! + \S{utils-pi} \cw{PI} The main Puzzles header file defines a macro \cw{PI} which expands @@ -18,6 +18,9 @@ #define STR_INT(x) #x #define STR(x) STR_INT(x) +/* An upper bound on the length of sprintf'ed integers (signed or unsigned). */ +#define MAX_DIGITS(x) (sizeof(x) * CHAR_BIT / 3 + 2) + /* NB not perfect because they evaluate arguments multiple times. */ #ifndef max #define max(x,y) ( (x)>(y) ? (x) : (y) ) |