So I claimed I was proficient in a number of languages on my resume, all of which I've barely used.
I think I can get away with some of it but I really think I need to know how to use C and Python well for the job. He said the job might require C# which is close enough to core C.
How do I become proficient with these languages in a week or so?
Also don't recommend me SICP. I tried reading a little and it was shit. Also what's this I hear about it only being good for Scheme programmers and giving everyone else bad programming habits?
This book is overhyped and useless for non-Scheme programmers. The obscure and non-intuitive syntax(with plenty of parenteheses) of Lisp + heavy abuse of recursion means people learn bad coding habits. If you want to learn practical programming use a book suited to your language of choice, or a language reference/manual.
Be able to hose Dr. Sosman in a technical debate on comp.lang.c. If you can slap him down enough times, he will offer you a decent engineering job at Oracle.
Name:
Anonymous2011-04-15 20:25
Don't do graphics programming, ever!
Name:
Anonymous2011-04-15 21:43
>>5
(I can't understand recursion, it must be bad coding habit!!!)
>>10
Recursion doesn't have to be bad. It has to be managed like any loop, naturally. I'm willing to bet you've seen what a bad loop does (doesnt work)? Make sure you have loops down, first. NO "-1"s in loops!!!! No -1 in top params/def.
DESCRIPTION ed is a line-oriented text editor. It is used to create, display, mod‐
ify and otherwise manipulate text files. red is a restricted ed: it
can only edit files in the current directory and cannot execute shell
commands.
If invoked with a file argument, then a copy of file is read into the
editor's buffer. Changes are made to this copy and not directly to file itself. Upon quitting ed, any changes not explicitly saved with
a `w' command are lost.
Editing is done in two distinct modes: command and input. When first
invoked, ed is in command mode. In this mode commands are read from
the standard input and executed to manipulate the contents of the edi‐
tor buffer. A typical command might look like:
,s/old/new/g
which replaces all occurrences of the string old with new.
When an input command, such as `a' (append), `i' (insert) or `c'
(change), is given, ed enters input mode. This is the primary means of
adding text to a file. In this mode, no commands are available;
instead, the standard input is written directly to the editor buffer.
Lines consist of text up to and including a newline character. Input
mode is terminated by entering a single period (.) on a line.
All ed commands operate on whole lines or ranges of lines; e.g., the `d' command deletes lines; the `m' command moves lines, and so on. It
is possible to modify only a portion of a line by means of replacement,
as in the example above. However even here, the `s' command is applied
to whole lines at a time.
In general, ed commands consist of zero or more line addresses, fol‐
lowed by a single character command and possibly additional parameters;
i.e., commands have the structure:
[address[,address]]command[parameters]
The address(es) indicate the line or range of lines to be affected by
the command. If fewer addresses are given than the command accepts,
then default addresses are supplied.
OPTIONS
-G Forces backwards compatibility. Affects the commands `G', `V', `f', `l', `m', `t', and `!!'.
-s Suppresses diagnostics. This should be used if ed's standard
input is from a script.
-p string
Specifies a command prompt. This may be toggled on and off
with the `P' command.
file Specifies the name of a file to read. If file is prefixed with
a bang (!), then it is interpreted as a shell command. In this
case, what is read is the standard output of file executed via sh(1). To read a file whose name begins with a bang, prefix
the name with a backslash (\). The default filename is set to file only if it is not prefixed with a bang.
LINE ADDRESSING
An address represents the number of a line in the buffer. ed maintains
a currentaddress which is typically supplied to commands as the
default address when none is specified. When a file is first read,
the current address is set to the last line of the file. In general,
the current address is set to the last line affected by a command.
A line address is constructed from one of the bases in the list below,
optionally followed by a numeric offset. The offset may include any
combination of digits, operators (i.e. + and -) and whitespace.
Addresses are read from left to right, and their values are computed
relative to the current address.
One exception to the rule that addresses represent line numbers is the
address 0 (zero). This means "before the first line", and is valid
wherever it makes sense.
An address range is two addresses separated either by a comma or semi‐
colon. The value of the first address in a range cannot exceed the
value of the second. If only one address is given in a range, then the
second address is set to the given address. If an n-tuple of addresses
is given where n>2, then the corresponding range is determined by the
last two addresses in the n-tuple. If only one address is expected,
then the last address is used.
Each address in a comma-delimited range is interpreted relative to the
current address. In a semicolon-delimited range, the first address is
used to set the current address, and the second address is interpreted
relative to the first.
The following address symbols are recognized.
. The current line (address) in the buffer.
$ The last line in the buffer.
n The nth, line in the buffer where n is a number in the range [0,$].
- The previous line. This is equivalent to -1 and may be
repeated with cumulative effect.
^n The nth previous line, where n is a non-negative number.
+ The next line. This is equivalent to +1 and may be repeated
with cumulative effect.
whitespacen
+n The nth next line, where n is a non-negative number. White‐ space followed by a number n is interpreted as +n.
, The first through last lines in the buffer. This is equivalent
to the address range 1,$.
; The current through last lines in the buffer. This is equiva‐
lent to the address range .,$.
/re/ The next line containing the regular expression re. The search
wraps to the beginning of the buffer and continues down to the
current line, if necessary. // repeats the last search.
?re? The previous line containing the regular expression re. The
search wraps to the end of the buffer and continues up to the
current line, if necessary. ?? repeats the last search.
'lc The line previously marked by a `k' (mark) command, where lc is
a lower case letter.
REGULAR EXPRESSIONS
Regular expressions are patterns used in selecting text. For example,
the ed command
g/string/
prints all lines containing string. Regular expressions are also used
by the `s' command for selecting old text to be replaced with new.
In addition to a specifying string literals, regular expressions can
represent classes of strings. Strings thus represented are said to be
matched by the corresponding regular expression. If it is possible for
a regular expression to match several strings in a line, then the left-
most longest match is the one selected.
The following symbols are used in constructing regular expressions:
c Any character c not listed below, including `{', '}', `(', `)',
`<' and `>', matches itself.
\c A backslash-escaped character c other than `{', '}', `(', `)',
`<', `>', `b', 'B', `w', `W', `+', and `?' matches itself.
. Matches any single character.
[char-class]
Matches any single character in char-class. To include a `]'
in char-class, it must be the first character. A range of
characters may be specified by separating the end characters of
the range with a `-', e.g., `a-z' specifies the lower case
characters. The following literal expressions can also be used
in char-class to specify sets of characters:
If `-' appears as the first or last character of char-class,
then it matches itself. All other characters in char-class
match themselves.
Patterns in char-class of the form:
[.col-elm.] or, [=[u]col-elm[/u]=]
where col-elm is a collating element are interpreted according
to locale(5) (not currently supported). See regex(3) for an
explanation of these constructs.
[^char-class]
Matches any single character, other than newline, not in char- class. char-class is defined as above.
^ If `^' is the first character of a regular expression, then it
anchors the regular expression to the beginning of a line.
Otherwise, it matches itself.
$ If `$' is the last character of a regular expression, it
anchors the regular expression to the end of a line. Other‐
wise, it matches itself.
\(re\) Defines a (possibly null) subexpression re. Subexpressions may
be nested. A subsequent backreference of the form `\n', where n is a number in the range [1,9], expands to the text matched
by the nth subexpression. For example, the regular expression
`\(a.c\)\1' matches the string `abcabc', but not `abcadc'.
Subexpressions are ordered relative to their left delimiter.
* Matches the single character regular expression or subexpres‐
sion immediately preceding it zero or more times. If '*' is
the first character of a regular expression or subexpression,
then it matches itself. The `*' operator sometimes yields
unexpected results. For example, the regular expression `b*'
matches the beginning of the string `abbb', as opposed to the
substring `bbb', since a null match is the only left-most
match.
\{n,m\}
\{n,\}
\{n\} Matches the single character regular expression or subexpres‐
sion immediately preceding it at least n and at most m times.
If m is omitted, then it matches at least n times. If the
comma is also omitted, then it matches exactly n times. If
any of these forms occurs first in a regular expression or sub‐
expression, then it is interpreted literally (i.e., the regular
expression `\{2\}' matches the string `{2}', and so on).
\<
\> Anchors the single character regular expression or subexpres‐
sion immediately following it to the beginning (\<) or ending
(\>) of a word, i.e., in ASCII, a maximal string of alphanu‐
meric characters, including the underscore (_).
The following extended operators are preceded by a backslash (\) to
distinguish them from traditional ed syntax.
\`
\' Unconditionally matches the beginning (\`) or ending (\') of a
line.
\? Optionally matches the single character regular expression or
subexpression immediately preceding it. For example, the regu‐
lar expression `a[bd]\?c' matches the strings `abc', `adc' and
`ac'. If \? occurs at the beginning of a regular expressions
or subexpression, then it matches a literal `?'.
\+ Matches the single character regular expression or subexpres‐
sion immediately preceding it one or more times. So the regu‐
lar expression `a\+' is shorthand for `aa*'. If \+ occurs at
the beginning of a regular expression or subexpression, then it
matches a literal `+'.
\b Matches the beginning or ending (null string) of a word. Thus
the regular expression `\bhello\b' is equivalent to
`\<hello\>'. However, `\b\b' is a valid regular expression
whereas `\<\>' is not.
\B Matches (a null string) inside a word.
\w Matches any character in a word.
\W Matches any character not in a word.
COMMANDS
All ed commands are single characters, though some require additional
parameters. If a command's parameters extend over several lines, then
each line except for the last must be terminated with a backslash (\).
In general, at most one command is allowed per line. However, most
commands accept a print suffix, which is any of `p' (print), `l' (list)
, or `n' (enumerate), to print the last line affected by the command.
An interrupt (typically ^C) has the effect of aborting the current com‐
mand and returning the editor to command mode.
ed recognizes the following commands. The commands are shown together
with the default address or address range supplied if none is specified
(in parenthesis).
(.)a Appends text to the buffer after the addressed line, which may
be the address 0 (zero). Text is entered in input mode. The
current address is set to last line entered.
(.,.)c Changes lines in the buffer. The addressed lines are deleted
from the buffer, and text is appended in their place. Text is
entered in input mode. The current address is set to last line
entered.
(.,.)d Deletes the addressed lines from the buffer. If there is a
line after the deleted range, then the current address is set
to this line. Otherwise the current address is set to the line
before the deleted range.
e file Edits file, and sets the default filename. If file is not
specified, then the default filename is used. Any lines in
the buffer are deleted before the new file is read. The cur‐
rent address is set to the last line read.
e !command
Edits the standard output of `!command', (see !command below).
The default filename is unchanged. Any lines in the buffer are
deleted before the output of command is read. The current
address is set to the last line read.
E file Edits file unconditionally. This is similar to the e command,
except that unwritten changes are discarded without warning.
The current address is set to the last line read.
f file Sets the default filename to file. If file is not specified,
then the default unescaped filename is printed.
(1,$)g/re/command-list
Applies command-list to each of the addressed lines matching a
regular expression re. The current address is set to the line
currently matched before command-list is executed. At the end
of the `g' command, the current address is set to the last line
affected by command-list.
Each command in command-list must be on a separate line, and
every line except for the last must be terminated by a back‐
slash (\). Any commands are allowed, except for `g', `G', `v',
and `V'. A newline alone in command-list is equivalent to a `p' command.
(1,$)G/re/
Interactively edits the addressed lines matching a regular
expression re. For each matching line, the line is printed,
the current address is set, and the user is prompted to enter a command-list. At the end of the `G' command, the current
address is set to the last line affected by (the last) command- list.
The format of command-list is the same as that of the `g' com‐
mand. A newline alone acts as a null command list. A single
`&' repeats the last non-null command list.
H Toggles the printing of error explanations. By default, expla‐
nations are not printed. It is recommended that ed scripts
begin with this command to aid in debugging.
h Prints an explanation of the last error.
(.)i Inserts text in the buffer before the current line. Text is
entered in input mode. The current address is set to the last
line entered.
(.,.+1)j
Joins the addressed lines. The addressed lines are deleted
from the buffer and replaced by a single line containing their
joined text. The current address is set to the resultant line.
(.)klc Marks a line with a lower case letter lc. The line can then
be addressed as 'lc (i.e., a single quote followed by lc ) in
subsequent commands. The mark is not cleared until the line is
deleted or otherwise modified.
(.,.)l Prints the addressed lines unambiguously. If invoked from a
terminal, ed pauses at the end of each page until a newline is
entered. The current address is set to the last line printed.
(.,.)m(.)
Moves lines in the buffer. The addressed lines are moved to
after the right-hand destination address, which may be the
address 0 (zero). The current address is set to the new
address of the last line moved.
(.,.)n Prints the addressed lines along with their line numbers. The
current address is set to the last line printed.
(.,.)p Prints the addressed lines. If invoked from a terminal, ed
pauses at the end of each page until a newline is entered. The
current address is set to the last line printed.
P Toggles the command prompt on and off. Unless a prompt was
specified by with command-line option -pstring, the command
prompt is by default turned off.
q Quits ed.
Q Quits ed unconditionally. This is similar to the q command,
except that unwritten changes are discarded without warning.
($)r file
Reads file to after the addressed line. If file is not speci‐
fied, then the default filename is used. If there was no
default filename prior to the command, then the default file‐
name is set to file. Otherwise, the default filename is
unchanged. The current address is set to the last line read.
($)r !command
Reads to after the addressed line the standard output of `!com‐
mand', (see the !command below). The default filename is
unchanged. The current address is set to the last line read.
(.,.)s/re/replacement/
(.,.)s/re/replacement/g
(.,.)s/re/replacement/n
Replaces text in the addressed lines matching a regular expres‐
sion re with replacement. By default, only the first match in
each line is replaced. If the `g' (global) suffix is given,
then every match to be replaced. The `n' suffix, where n is a
positive number, causes only the nth match to be replaced. It
is an error if no substitutions are performed on any of the
addressed lines. The current address is set to the last line
affected.
re and replacement may be delimited by any character other than
space, newline and the characters used by the form of the `s'
command shown below. If one or two of the last delimiters is
omitted, then the last line affected is printed as though the
print suffix `p' were specified.
An unescaped `&' in replacement is replaced by the currently
matched text. The character sequence `\m', where m is a number
in the range [1,9], is replaced by the mth backreference
expression of the matched text. If replacement consists of a
single `%', then replacement from the last substitution is
used. Newlines may be embedded in replacement if they are
escaped with a backslash (\).
(.,.)s Repeats the last substitution. This form of the `s' command
accepts a count suffix `n', and any combination of the charac‐
ters `r', `g', and `p'. If a count suffix `n' is given, then
only the nth match is replaced. The `r' suffix causes the reg‐
ular expression of the last search to be used instead of the
that of the last substitution. The `g' suffix toggles the
global suffix of the last substitution. The `p' suffix toggles
the print suffix of the last substitution. The current address
is set to the last line affected.
(.,.)t(.)
Copies (i.e., transfers) the addressed lines to after the
right-hand destination address, which may be the address 0
(zero). The current address is set to the last line copied.
u Undoes the last command and restores the current address to
what it was before the command. The global commands `g', `G', `v', and `V'. are treated as a single command by undo. `u' is
its own inverse.
(1,$)v/re/command-list
Applies command-list to each of the addressed lines not match‐
ing a regular expression re. This is similar to the `g' com‐
mand.
(1,$)V/re/
Interactively edits the addressed lines not matching a regular
expression re. This is similar to the `G' command.
(1,$)w file
Writes the addressed lines to file. Any previous contents of file is lost without warning. If there is no default filename,
then the default filename is set to file, otherwise it is
unchanged. If no filename is specified, then the default file‐
name is used. The current address is unchanged.
(1,$)wq file
Writes the addressed lines to file, and then executes a `q'
command.
(1,$)w !command
Writes the addressed lines to the standard input of `!command',
(see the !command below). The default filename and current
address are unchanged.
(1,$)W file
Appends the addressed lines to the end of file. This is simi‐
lar to the `w' command, expect that the previous contents of
file is not clobbered. The current address is unchanged.
(.)x Copies (puts) the contents of the cut buffer to after the
addressed line. The current address is set to the last line
copied.
(.,.)y Copies (yanks) the addressed lines to the cut buffer. The cut
buffer is overwritten by subsequent `y', `s', `j', `d', or `c'
commands. The current address is unchanged.
(.+1)zn Scrolls n lines at a time starting at addressed line. If n is
not specified, then the current window size is used. The cur‐
rent address is set to the last line printed.
!command
Executes command via sh(1). If the first character of command
is `!', then it is replaced by text of the previous `!command'.
ed does not process command for backslash (\) escapes. How‐
ever, an unescaped `%' is replaced by the default filename.
When the shell returns from execution, a `!' is printed to the
standard output. The current line is unchanged.
(.,.)# Begins a comment; the rest of the line, up to a newline, is
ignored. If a line address followed by a semicolon is given,
then the current address is set to that address. Otherwise,
the current address is unchanged.
($)= Prints the line number of the addressed line.
(.+1)newline
Prints the addressed line, and sets the current address to that
line.
FILES
ed.hup The file to which ed attempts to write the buffer if the ter‐
minal hangs up.
B. W. Kernighan and P. J. Plauger, SoftwareToolsinPascal, Addison-
Wesley, 1981.
LIMITATIONS ed processes file arguments for backslash escapes, i.e., in a file‐
name, any character preceded by a backslash (\) is interpreted liter‐
ally.
If a text (non-binary) file is not terminated by a newline character,
then ed appends one on reading/writing it. In the case of a binary
file, ed does not append a newline on reading/writing.
Per line overhead: 2 pointers, 1 long int, and 1 int.
DIAGNOSTICS
When an error occurs, if ed's input is from a regular file or here doc‐
ument, then it exits, otherwise it prints a `?' and returns to command
mode. An explanation of the last error can be printed with the `h'
(help) command.
Attempting to quit ed or edit another file before writing a modified
buffer results in an error. If the command is entered a second time,
it succeeds, but any changes to the buffer are lost.
ed exits with 0 if no errors occurred; otherwise >0.
>>23
No he really said that. Well it was a recruiter for the company who said it. He sounded like he knew a lot about which programming languages are good for what though.
>>23
Sure, why not, you can write C in any C family language.
The best way to write fast Java code is to pretend you're writing C, I wouldn't be surprised if C# was the same.
Name:
Anonymous2011-04-17 19:45
You know there is a perfect book of the C language itself. Also, it is written by the creators of C language. It is known as K&R, and you can find it at amazon or somewhere like that by searching for The C Programming Language.
It is the only a-must-read book on C. Read it. Then read SICP.
Name:
Anonymous2011-04-17 19:55
Not OP but I don't want to make a new thread for this.
What's wrong with
#include <stdio.h>
int sum(int* x, int i);
int main() {
int i = 0;
int* v;
v = malloc(sizeof(int) * 4);
do {
printf("Element %d: ", i); scanf("%d", &v[i]);
i++;
if(i%4==0) v = malloc(sizeof(int) * (i+4));
}while(v[i-1] > 0);
int s = sum(v, i-1);
printf("Sum: %d\n", s);
return(0); }
int sum(int x[], int n) {
int s = 0;
int i;
for(i = 0; i < n; i++) {
s += x[i];
}
return(s);
}
This should be int main(void) or int main(int argc, char **argv)
Any ANSI C compiler with the warnings on would have told you this.
"v = malloc(sizeof(int) * 4);"
What if malloc fails? I can think of trivial example of when something like this could happen.
" printf("Element %d: ", i); "
Undefined behavior. Ie, there some are systems where you won't see the output until *after* the program exits.
" scanf("%d", &v[i]);"
You don't check scanf() for abritrary input.
Should I go on?
Cripes, have you ever actually take a programming class you stupid fucker? I bet now. Maybe you should just shut up, and do what you know best. Discussing jewish zionism.
If anyone can help me out I don't understand what "Undefined behavior. Ie, there some are systems where you won't see the output until *after* the program exits." means.
I'm kind of new at this. I did take a programming course but the class ended before getting to better programming habits.
>>47
do not listen to him. he was just pointing to stupid things while missing the obvious error.
use realloc instead of second malloc. you are malloc ing new memory and lose the old address (which gives a memory leak btw) this new address points to a new memory location which is filled with garbage. it does not contain old data.
>>48
Ok, I did end up getting the program to work but I am still curious about the errors that guy mentioned. I understand all the problems except for the one I quoted (though I also don't know how to fix the scanf problem.)
>>52
Yes, but most modern computer use this concept called virtual memory. On top of that, most os's will fucking load the damn program into the cache before it executes it.
Name:
Anonymous2011-04-18 4:08
>>39
[quote]Undefined behavior. Ie, there some are systems where you won't see the output until *after* the program exits.[/quote]
Just use fflush(3) or setvbuf(3) if you're seriously worried about this.
>>49
[quote]I also don't know how to fix the scanf problem.[/quote] scanf(3) returns the number of tokens which have been successfully scanned. If this number doesn't match the number of tokens in your format string, you know have a problem.
>>59
That's not what I said, faggot. That's what the recruiterbro said. The guy that is hired to find applicants. He also said C++ is really similar to C.