Created
August 17, 2018 00:42
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Forth number formatting, ported to C
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#include <stdio.h> | |
#include <string.h> | |
#define NFMT_BUF_LEN 32 | |
const char nfmt_set[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; | |
char nfmt_base; | |
char nfmt_buf[NFMT_BUF_LEN+1] = {0}; | |
char* nfmt_ptr; | |
// equivalent to BASE <# in Forth | |
void nfmt_init(char base) { | |
nfmt_base = base; | |
nfmt_buf[NFMT_BUF_LEN] = '\0'; | |
nfmt_ptr = &nfmt_buf[NFMT_BUF_LEN]; | |
} | |
// equivalent to HOLD in Forth | |
void nfmt_hold(char c) { | |
--nfmt_ptr; | |
*nfmt_ptr = c; | |
} | |
// equivalent to HOLDS in Forth | |
void nfmt_holds(char* c) { | |
int len = strlen(c); | |
nfmt_ptr -= len; | |
memcpy(nfmt_ptr, c, len); | |
} | |
// equivalent to # in Forth | |
void nfmt_digit(unsigned long* n) { | |
char digit = nfmt_set[*n % nfmt_base]; | |
*n /= nfmt_base; | |
nfmt_hold(digit); | |
} | |
// equivalent to #S in Forth | |
void nfmt_digits(unsigned long* n) { | |
do { | |
nfmt_digit(n); | |
} while (*n != 0); | |
} | |
// equivalent to #> in Forth | |
char* nfmt_end() { | |
return nfmt_ptr; | |
} | |
void thousands(unsigned long* n) { | |
while (*n > 999) { | |
nfmt_digit(n); | |
nfmt_digit(n); | |
nfmt_digit(n); | |
nfmt_hold(','); | |
} | |
nfmt_digits(n); | |
} | |
char* number(long n) { | |
char sign = 0; | |
if (n < 0) { | |
sign = 1; | |
n = -n; | |
} | |
nfmt_init(10); | |
thousands(&n); | |
if (sign) nfmt_hold('-'); | |
return nfmt_end(); | |
} | |
char* cents(long n) { | |
char sign = 0; | |
if (n < 0) { | |
sign = 1; | |
n = -n; | |
} | |
nfmt_init(10); | |
if (sign) nfmt_hold(')'); // accounting-style negative numbers | |
nfmt_digit(&n); | |
nfmt_digit(&n); | |
nfmt_hold('.'); | |
thousands(&n); | |
nfmt_hold('$'); | |
if (sign) nfmt_hold('('); | |
return nfmt_end(); | |
} | |
char* hex(unsigned long n) { | |
nfmt_init(16); | |
nfmt_digits(&n); | |
nfmt_holds("0x"); | |
return nfmt_end(); | |
} | |
int main() { | |
puts(number(25252)); // 25,252 | |
puts(number(-500)); // -500 | |
puts(cents(1234567890)); // $12,345,678.90 | |
puts(cents(-200000)); // ($2,000.00) | |
puts(hex(32768)); // 0x8000 | |
puts(hex(-1)); // 0xFFFFFFFFFFFFFFFF | |
} |
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