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-rw-r--r--printf.c106
1 files changed, 82 insertions, 24 deletions
diff --git a/printf.c b/printf.c
index a6153d8..5a15d12 100644
--- a/printf.c
+++ b/printf.c
@@ -28,7 +28,7 @@ flag: - left justify, pad right w/ blanks DONE
width: (field width) DONE
-prec: (precision) no
+prec: (precision) DONE
conv: d,i decimal int DONE
u decimal unsigned DONE
@@ -43,7 +43,7 @@ mod: N near ptr DONE
F far ptr no
h short (16-bit) int DONE
l long (32-bit) int DONE
- L long long (64-bit) int no
+ L/ll long long (64-bit) int no
*****************************************************************************/
#include <string.h> /* strlen() */
#include <stdio.h> /* stdout, putchar(), fputs() (but not printf() :) */
@@ -64,6 +64,10 @@ mod: N near ptr DONE
2^64-1 in base 8 has 22 digits (add 2 for trailing NUL and for slop) */
#define PR_BUFLEN 24
+#ifndef max
+#define max(a,b) ((a > b) ? a : b)
+#endif
+
typedef int (*fnptr_t)(unsigned c, void **helper);
/*****************************************************************************
name: do_printf
@@ -73,12 +77,12 @@ returns:total number of characters output
*****************************************************************************/
int do_printf(const char *fmt, va_list args, fnptr_t fn, void *ptr)
{
- unsigned flags, actual_wd, count, given_wd;
+ unsigned flags, length, count, width, precision;
unsigned char *where, buf[PR_BUFLEN];
unsigned char state, radix;
long num;
- state = flags = count = given_wd = 0;
+ state = flags = count = width = precision = 0;
/* begin scanning format specifier list */
for(; *fmt; fmt++)
{
@@ -102,13 +106,13 @@ int do_printf(const char *fmt, va_list args, fnptr_t fn, void *ptr)
{
fn(*fmt, &ptr);
count++;
- state = flags = given_wd = 0;
+ state = flags = width = precision = 0;
break;
}
if(*fmt == '-')
{
if(flags & PR_LJ)/* %-- is illegal */
- state = flags = given_wd = 0;
+ state = flags = width = precision = 0;
else
flags |= PR_LJ;
break;
@@ -126,15 +130,26 @@ int do_printf(const char *fmt, va_list args, fnptr_t fn, void *ptr)
case 2:
if(*fmt >= '0' && *fmt <= '9')
{
- given_wd = 10 * given_wd +
- (*fmt - '0');
+ width = 10 * width + (*fmt - '0');
break;
}
-/* not field width: advance state to check if it's a modifier */
+/* not a field width: advance state to check if it's field precision */
state++;
/* FALL THROUGH */
-/* STATE 3: AWAITING MODIFIER CHARS (FNlh) */
+/* STATE 3: AWAITING (NUMERIC) FIELD PRECISION */
case 3:
+ if(*fmt == '.')
+ ++fmt;
+ if(*fmt >= '0' && *fmt <= '9')
+ {
+ precision = 10 * precision + (*fmt - '0');
+ break;
+ }
+/* not field precision: advance state to check if it's a modifier */
+ state++;
+ /* FALL THROUGH */
+/* STATE 4: AWAITING MODIFIER CHARS (FNlh) */
+ case 4:
if(*fmt == 'F')
{
flags |= PR_FP;
@@ -155,8 +170,8 @@ int do_printf(const char *fmt, va_list args, fnptr_t fn, void *ptr)
/* not modifier: advance state to check if it's a conversion char */
state++;
/* FALL THROUGH */
-/* STATE 4: AWAITING CONVERSION CHARS (Xxpndiuocs) */
- case 4:
+/* STATE 5: AWAITING CONVERSION CHARS (Xxpndiuocs) */
+ case 5:
where = buf + PR_BUFLEN - 1;
*where = '\0';
switch(*fmt)
@@ -225,22 +240,36 @@ OK, I found my mistake. The math here is _always_ unsigned */
num = (unsigned long)num / radix;
}
while(num != 0);
+/* for integers, precision functions like width, but pads with zeros */
+ if (precision != 0)
+ {
+ width = max(width, precision);
+ if (precision > strlen(where))
+ flags |= PR_LZ;
+ precision = 0;
+ }
goto EMIT;
case 'c':
/* disallow pad-left-with-zeroes for %c */
flags &= ~PR_LZ;
where--;
*where = (unsigned char)va_arg(args, int);
- actual_wd = 1;
+ length = 1;
goto EMIT2;
case 's':
/* disallow pad-left-with-zeroes for %s */
flags &= ~PR_LZ;
where = va_arg(args, unsigned char *);
EMIT:
- actual_wd = strlen((const char *)where);
+ length = strlen((const char *)where);
+/* if string is longer than precision, truncate */
+ if ((precision != 0) && (precision < length))
+ {
+ length = precision;
+ precision = 0;
+ }
if(flags & PR_WS)
- actual_wd++;
+ length++;
/* if we pad left with ZEROES, do the sign now */
if((flags & (PR_WS | PR_LZ)) ==
(PR_WS | PR_LZ))
@@ -251,12 +280,12 @@ EMIT:
/* pad on left with spaces or zeroes (for right justify) */
EMIT2: if((flags & PR_LJ) == 0)
{
- while(given_wd > actual_wd)
+ while(width > length)
{
fn(flags & PR_LZ ?
'0' : ' ', &ptr);
count++;
- given_wd--;
+ width--;
}
}
/* if we pad left with SPACES, do the sign now */
@@ -266,16 +295,17 @@ EMIT2: if((flags & PR_LJ) == 0)
count++;
}
/* emit string/char/converted number */
- while(*where != '\0')
+ for(int i = (flags & PR_WS) ? 1 : 0;
+ i < length; ++i)
{
fn(*where++, &ptr);
count++;
}
/* pad on right with spaces (for left justify) */
- if(given_wd < actual_wd)
- given_wd = 0;
- else given_wd -= actual_wd;
- for(; given_wd; given_wd--)
+ if(width < length)
+ width = 0;
+ else width -= length;
+ for(; width; width--)
{
fn(' ', &ptr);
count++;
@@ -285,7 +315,7 @@ EMIT2: if((flags & PR_LJ) == 0)
break;
}
default:
- state = flags = given_wd = 0;
+ state = flags = width = precision = 0;
break;
}
}
@@ -369,7 +399,35 @@ int main(void)
printf("<%-8s> and <%8s> justified strings\n", "left", "right");
- printf("short signed: %hd, short unsigned: %hu\n", -1, -1);
+ printf("short signed: %hd, short unsigned: %hu\n\n", -1, -1);
+
+ char str[] = "abcdefghijklmnopqrstuvwxyz";
+ printf("%8s\n", str); /* abcdefghijklmnopqrstuvwxyz */
+ printf("%8.32s\n", str); /* abcdefghijklmnopqrstuvwxyz */
+ printf("%8.16s\n", str); /* abcdefghijklmnop */
+ printf("%8.8s\n", str); /* abcdefgh */
+ printf("%8.4s\n", str); /* abcd */
+ printf("%4.8s\n", str); /* abcdefgh */
+ printf("%.8s\n", str); /* abcdefgh */
+ printf("%8s\n", "abcd"); /* abcd */
+ printf("%8.8s\n", "abcd"); /* abcd */
+ printf("%4.8s\n", "abcd"); /* abcd */
+ printf("%.8s\n", "abcd"); /* abcd */
+ printf("%.0s\n", str); /* */
+ printf("\n");
+
+ int num = 123456;
+ printf("%016d\n", num); /* 0000000000123456 */
+ printf("%16d\n", num); /* 123456 */
+ printf("%8d\n", num); /* 123456 */
+ printf("%8.16d\n", num); /* 0000000000123456 */
+ printf("%8.8d\n", num); /* 00123456 */
+ printf("%8.4d\n", num); /* 123456 */
+ printf("%4.4d\n", num); /* 123456 */
+ printf("%.16d\n", num); /* 0000000000123456 */
+ printf("%.8d\n", num); /* 00123456 */
+ printf("%.4d\n", num); /* 123456 */
+
return 0;
}
#else
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 11:52:46 +0000