2014/1/14-2/5 [Computer/SW/Languages/C_Cplusplus] UID:54763 Activity:nil | 1/14 Why is NULL defined to be "0" in C++ instead of "((void *) 0)" like in
C? I have some overloaded functtions where one takes an integer
parameter and the other a pointer parameter. When I call it with
"NULL", the compiler matches it with the integer version instead of
the pointer version which is a problem. Other funny effect is that
sizeof(NULL) is different from sizeof(myPtr). Thanks.
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2013/4/29-5/18 [Computer/SW/Languages/C_Cplusplus, Computer/SW/Compilers] UID:54665 Activity:nil | 4/29 Why were C and Java designed to require "break;" statements for a
"case" section to terminate rather than falling-through to the next
section? 99% of the time poeple want a "case" section to terminate.
In fact some compilers issue warning if there is no "break;" statement
in a "case" section. Why not just design the languages to have
termination as the default behavior, and provide a "fallthru;"
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2012/7/19-11/7 [Computer/SW/Languages/C_Cplusplus] UID:54439 Activity:nil | 7/19 In C or C++, how do I write the code of a function with variable
number of parameters in order to pass the variable parameters to
another function that also has variable number of parameters? Thanks.
\_ The usual way (works on gcc 3.0+, Visual Studio 2005+):
#define foo(fmt, ...) printf(fmt, ##__VA_ARGS__)
The cool new way (works on gcc 4.3+):
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2011/3/7-4/20 [Computer/SW/Languages/C_Cplusplus] UID:54056 Activity:nil | 3/7 I have a C question. I have the following source code in two identical
files t.c and t.cpp:
#include <stdlib.h>
int main(int argc, char *argv[]) {
const char * const * p1;
const char * * p2;
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2011/2/5-19 [Computer/SW/Languages/C_Cplusplus] UID:54027 Activity:nil | 2/4 random C programming/linker fu question. If I have
int main() { printf("%s is at this adddr %p\n", "strlen", strlen); }
and soda's /proc/sys/kernel/randomize_va_space is 2 (eg; on)
why is strlen (or any other libc fn) at the same address every time?
\_ I don't pretend to actually know the right answer to this, but
could it have something to do with shared libraries?
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2010/2/12-3/9 [Computer/SW/Languages/C_Cplusplus] UID:53708 Activity:nil | 2/12 I need a way to make a really big C++ executable (~200MBs) that does
nothing. No static initialization either. Any ideas?
\_ static link in lots of libraries?
\_ #define a i=0; i=0; i=0; i=0; i=0; i=0; i=0; i=0; i=0; i=0;
#define b a a a a a a a a a a
#define c b b b b b b b b b b
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2009/8/7-14 [Computer/SW/Languages/C_Cplusplus, Computer/SW/Languages/Java] UID:53252 Activity:high | 8/6 In C one can do "typedef int my_index_t;". What's the equivalent in
C#? Thanks.
\_ C#? Are you serious? Is this what the class of 2009 learn?
\_ No. I have to learn .NET code at work. I am Class of '93.
\_ python is what 2009 learns, see the motd thread about recent
cal courses and languages
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2009/7/21-24 [Computer/SW/Languages/Java] UID:53168 Activity:moderate | 7/20 For those who care btw, it looks like eclipse is now A Standard Tool
at UCB ugrad cs, probably replaced emacs. Furthermore, people get
angry at seeing Makefiles, (since eclispe takes care of that). I
guess it's just a sign of the times.
\_ The more people at my work use eclipse the less the code is
managable in emacs. I'm not sure which application's fault
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2011/10/26-12/6 [Computer/SW/Unix] UID:54202 Activity:nil | 10/24 What's an easy way to see if say column 3 of a file matches a list of
expressions in a file? Basically I want to combine "grep -f <file>"
to store the patterns and awk's $3 ~ /(AAA|BBB|CCC)/ ... I realize
I can do this with "egrep -f " and use regexp instead of strings, but
was wondering if there was some magic way to do this.
\_ UNIX has no magic. Make a shell script to produce the ask or egrep
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2008/7/14-16 [Computer/SW/Languages/Perl, Computer/SW/Unix] UID:50557 Activity:moderate | 7/14 Shell Programming question: I want to call a script with 1 arg
and have it figure out whether $1 is a MAC address or an IP address
and then do call the appropriate function. What is the best way
to do this, given that sh/bash/ksh do not have something like
the =~ in perl. Check for exit status of grep, or is there a
a better way? For the moment, let's just say the two tests are:
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2005/3/2-3 [Computer/SW/Unix] UID:36496 Activity:high | 3/2 Is there a way to do "grep p1 file | grep p2" with one grep without
piping? ie, "grep p1&&p2 file"? Thx.
\_ use egrep? man egrep. Look for egrep -e
\_ Can I write an alias where I can say "mygrep p1 p2 p3 ... file",
where I can specify variable number of patterns, with the last
one being the filename?
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2004/9/14 [Computer/SW/Unix] UID:33516 Activity:moderate 50%like:35981 | 9/13 How can I get grep to serach for the characters '--' or '->'
(without the single quotes)? grep '--' * doesn't work. Thanks.
\- egrep -e '<expression>' --psb
\_ grep -- '--' *
(the first -- indicates the end of the list of options)
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2004/5/31 [Computer/SW/Languages/Perl] UID:30503 Activity:insanely high | 5/30 Let's say I have a directory full of subdirectories, each of which
has a number of files in it. How can I delete all subdirectories that
have, say, less than 10 files in them?
\_ fewer
\_ There's no single standard command that will do this. You'll
need to write something that will count files per directory,
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2004/3/23-24 [Computer/SW/Unix] UID:12817 Activity:very high | 3/23 What's the easiest way to find all files on a unix box that contain
both the words 'imap' and 'pop' on different lines. I'm trying to
find a courier authd config file that I swear had lines for turning
on and off different protocols (pop3 and imapd) but I can't find it
anywhere. and I can't find any references to it. -brett
\_ hrm.
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2003/6/10-11 [Computer/SW/Unix] UID:28691 Activity:high | 6/10 I want to grep for the ocurrance of the ']' and '[' character in a file
I've tried all sorts of quoting on the command line, everything seems
to give a ayntax or 'unmatched' error. How can I do this?
\_ grep '\['
\_ to search for both, use "egrep '\[|\]'<filename>" -jnat
\_ That doesn't seem to work as an "or" perhaps the version
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2003/5/5-6 [Computer/SW/Unix] UID:28340 Activity:high | 5/5 Given a file, what is the best way to see all lines AFTER (and
including) a keyword?
\_ sed -n '/keyword/,$p' file
\_ agrep?
\_ perl -ne 'if ($p) {print;} elsif (/keyword/) {$p=1;print;}' file
\_ thanks. When do you use perl, sed, awk, egrep?
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2002/11/15-16 [Computer/SW/Unix] UID:26553 Activity:moderate | 11/15 I want to remove all lines in a tex file that have been commented out
by a % at the beginning Any fast and easy way to do this?
Sorry no time to RTFM. Ok tnx.
\_ egrep -v '^\%' file > file.new
\_ grep -v ^% file > file.new
conserve keystrokes. ride bike
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