From d8c9ddf97c92d9dd3146a478c04b96b996d6d5c4 Mon Sep 17 00:00:00 2001 From: zlg Date: Sat, 20 Apr 2013 07:33:45 -0500 Subject: Solve Exercise 3-5: itob --- ch3/3-05_itob.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 ch3/3-05_itob.c (limited to 'ch3') diff --git a/ch3/3-05_itob.c b/ch3/3-05_itob.c new file mode 100644 index 0000000..58066e5 --- /dev/null +++ b/ch3/3-05_itob.c @@ -0,0 +1,85 @@ +#include +#include +#include + +/* The C Programming Language: 2nd Edition + * + * Exercise 3-5: Write the function itob(n,s,b) that converts the integer n + * into a base b character representation in the string s. In particular, + * itob(n,s,16) formats n as a hexadecimal integer in s. + * + * Answer: Retool the itoa() function written for 3-4 to take an additional + * argument, then add a few more checks and account for ASCII's 7-character + * distance between '9' and 'A', which makes bases higher than 16 function + * without a large switch statement. + */ + +void reverse(char s[]) { + int c, i, j; + + for (i = 0, j = strlen(s)-1; i < j; i++, j--) { + c = s[i]; + s[i] = s[j]; + s[j] = c; + } +} + +void itob(int n, char s[], unsigned b) { + int i, sign, min, rem; // Add 'min' for later use + + if ((sign = n) < 0) { + /* Detect this and add one so it can properly be made positive */ + if (n == INT_MIN) { + n += 1; + min = 1; + } + n = -n; + } + i = 0; + if (b > 1) { + do { + /* If it's the first iteration of the loop and we've established + * that n == INT_MIN, we need to add one to the resulting string for it + * to be displayed properly. */ + rem = n % b; + if (rem > 9) { + rem += 7; + } + if (i == 0 && min == 1) { + s[i++] = rem + '1'; + } else { + s[i++] = rem + '0'; + } + } while ((n /= b) > 0); + /* This is annoying, but to make hex numbers right, you have to account + * for the +1 added to the final number causing bit flipping */ + if (min == 1) { + for (i = 0; s[i] != '\0'; i++) { + if (s[i] == '-') { + continue; + } + if (i != 0 && s[i - 1] == '0' + (b + 7)) { + s[i] += 1; + s[i - 1] = '0'; + } + } + } + } + if (sign < 0) { + s[i++] = '-'; + } + s[i] = '\0'; + reverse(s); +} + +int main() { + int tests[5] = {INT_MIN, INT_MAX, -300, 172, 38478235}; + char st[101] = ""; + int i; + + for (i = 0; i < 5; i++) { + itob(tests[i], st, 16); + printf("%12d in string form is %12s\n", tests[i], st); + } + return 0; +} -- cgit v1.2.3-54-g00ecf 3f91db5a9982e2816de649e9bc4ef6&showmsg=1&follow=1'>src/vgstash (unfollow)
AgeCommit message (Collapse)AuthorFilesLines
2018-10-06Remove ID field from DBzlg2-33/+43
The sqlite database already uses a game's title and system as the primary keys. Row IDs are redundant.
2018-10-06cli: change "Status" heading to "Progress"zlg2-36/+40
2018-09-29Bump to 0.3alpha5 for PyPIzlg1-1/+1
2018-09-29cli: Add pretty printing to 'list' commandzlg3-17/+107
Also add the "--width" option to specify the maximum width of the table.
2018-09-08setup.py: Bump to alpha4 for PyPIzlg1-1/+1
2018-09-08cli: add '--raw' option to list commandzlg2-9/+45
Add '--raw' option to the list command, in addition to proper note expansion. Newline characters in notes are escaped to be friendly to scripting. This option may be shortened to '-r' at the user's convenience. In raw output mode, the information is formatted in plain pipe-delimited strings, one line per row: title|system|ownership|progress|notes ownership and progress are printed in their numeric form, consistent with the OWNERSHIP and PROGRESS dictionaries in the vgstash package. An empty notes field will result in a line ending with a pipe and no whitespace following it.
2018-09-08Add remaining filters to vgstash packagezlg1-2/+11
2018-09-04Update LICENSE to match setup.pyzlg1-80/+67
Whoops.
2018-09-03Branch off from master with pytest, tox, clickzlg16-778/+779
This commit is huge, but contains everything needed for a "proper" build system built on pytest + tox and a CLI built with click. For now, this branch will contain all new vgstash development activity until it reaches feature parity with master. The CLI is installed to pip's PATH. Only the 'init', 'add', and 'list' commands work, with only two filters. This is pre-alpha software, and is therefore not stable yet.
2018-03-18Flesh out filter types and ownership statuszlg3-82/+144
It's time for a refactor to a module; the functionality and interface are clashing.
2018-03-18README.mdown: break line correctlyzlg1-1/+1
2018-03-18add 'playlog' list filterzlg2-2/+9
This filter is used to get an idea of which games you're currently playing through, so you can prioritize games to play when you're bored and detect it when you've beaten a game but haven't marked it as such.
2018-03-13Update helpers a bitzlg1-2/+9
At present, user modification is needed to make these seamless. vgup() may need to be axed in favor of telling the user to make an alias.
2018-03-13Make VGSTASH_DB_LOCATION point to a filezlg2-21/+20
It used to point to a directory, which would then look for .vgstash.db. This behavior was kind of backwards and I don't remember why I did it that way. This change gives users more control over where they put their DB. Be sure to update your environment variable if you have it set!
2016-11-18Remove settings from helpers.shZe Libertine Gamer1-5/+0
Sourcing them in .bash_profile screws up login if they're set.
2016-11-15Correct phrasing in README.Ze Libertine Gamer1-4/+4
2016-11-13DerpZe Libertine Gamer1-0/+1
2016-11-03Improve error handling in shell scriptsZe Libertine Gamer4-3/+23
2016-10-24Correct run_again, add recursionZe Libertine Gamer1-0/+4
Loops and functions -- oh my, what a useful combination. :)
2016-10-21Add quotes to correct behavior for arglistZe Libertine Gamer1-1/+1
2016-10-14updater.sh: add recursion, error handlingZe Libertine Gamer1-43/+101
2016-10-14Correct pipe-handling behaviorZe Libertine Gamer1-1/+9
2016-10-12Clarify a method to move between platformsZe Libertine Gamer1-2/+5
Also correct a typo.