So i have a data file that contains a couple of lines that I am using for testing purposes. The data file contains this:
typedef enum A
{
enum A = 0;
enum B = 1;
}
A;
typedef enum B
{
enum A = 1;
enum B = 2;
}
B;
My code consists of this:
open(DATA, "<file.txt") or die "Couldn't open file file.txt, $!";
while(<DATA>){
print if /^(.*)(enum)(.*)$/;
}
I want to compare the values of A and A in each typedef and print an error suggesting compile error. How can i store these regex search results as variables?
Thanks
Just store the values returned from the match in list context (see perlop for details):
Keep a hash of declared variable names, report the error if an already declared name appears again:
my %declared;
while (<DATA>) {
if (my ($name) = /\b enum \s+ (\w+)/x) {
die "$name re-declared" if $declared{$name};
$declared{$name} = 1;
}
}
Related
Having this:
foo.pl:
#!/usr/bin/perl -w
#heds = map { /_h.+/ and s/^(.+)_.+/$1/ and "$_.hpp" } #ARGV;
#fls = map { !/_h.+/ and "$_.cpp" } #ARGV;
print "heds: #heds\nfls: #fls";
I want to separate headers from source files, and when I give input:
$./foo.pl a b c_hpp d_hpp
heds: e.hpp f.hpp
fls: e.cpp f.cpp a.cpp b.cpp
The headers are correctly separated, however the files are taken all. Why? I have applied the negative regex !/_h.+/ in the mapping so the files with *_h* should not be taken in account, but they are. Why so? and how to fix it?
Does not work even this:
#fls = map { if(!/_h.+/){ "$_.cpp" } } #ARGV;
still takes every files, despite the condition
The map { } for #heds includes a substitution on the $1 argument and changes it. Just reorder the mapppings to avoid the effect on #fls and you get the desired result. Though, if you need to access #ARGV after these mappings it is not the original #ARGV anymore, like in your example code.
#!/usr/bin/perl -w
#fls = map { !/_h.+/ and "$_.cpp" } #ARGV;
#heds = map { /_h.+/ and s/^(.+)_.+/$1/ and "$_.hpp" } #ARGV;
print "heds: #heds\nfls: #fls\n";
does anybody know how to get struct from line? For example, i have struct:
struct Variable {
Variable(){}
string m_name = "";
uint_16 value = 0;
string comments = "";
}
And some variants of line:
string line = "foo 0x22 #Comments"; //hex value
or
string line = "foo 222 #Comments"; //decimal value
or
string line = "foo ((1<4)&2) #Comments"; //expression value
or
string line = "foo ((1<4)&2)"; //without comment
The question is, should i use syntax analysis? Thanks.
Assuming all your fields are separated by a common delimiter (And that I've understood your question correctly), just break up the input string at the delimiters and consume them with string conversion functions. something like:
Variable parseVariable(const std::string& line)
{
Variable variable;
// You must define 'split'
std::vector<std::string> inputFields = split(line, " ");
variable.m_name = inputFields[0];
// You must also define 'convertStringToUint16'
variable.value = convertStringToUint16(inputFields[1]);
if(inputFields.size() > 2)
{
variable.comments = inputFields[2];
}
return variable;
}
Disclaimer: this code has not been tested
Now, regarding your use of the term "expression" I am worried that you may want to be able to evaluate arbitrary expressions for the value variable. If so, I recommend you define a VERY small scope of expressions that can be evaluated, as even simple mathematical expressions require decent work to process correctly.
I want to add in a .C file incase its not present. Using Perl
MY CODE SNIPPET
my $flag = 0;
my $pos = 0;
open(FILE, $input) or die $!;
my #lines = <FILE>;
foreach(#lines)
{
$pos++;
#checks for #include where it can add stdint.h
if ($_ =~ (m/#include/))
{
#prevents multiple addition for each header file
if($flag == 0)
{
#checks whether stdint already present or not
unless($_ =~ m/#include <stdint.h>/ )
{
splice #lines,$pos,0,"#include <stdint.h>"."\n";
$flag = 1;
}
}
}
}
But my code is adding stdint.h everytime it runs which means multiple addition for every run.
whats wrong with the code
unless($_ =~ m/#include <stdint.h>/){
doesn't work even if i use
unless($_ =~ m/<stdint.h>/){
Imagine you have this C file:
#include <stdio.h>
#include <stdint.h>
int main(int argc, char ** argv) {
return 0;
}
What is supposed to happen when this goes through your script?
Nothing, because is already included
What actually happens though? This is where learning to use the Perl debugger or simply tracing by hand is really useful.
flag and pos are initialized to 0. The first line in the file is #include <stdio.h> which is not #include <stdint.h>, so your code immediately assumes the file is missing and adds it.
So, in your above code you insert #include <stdint.h> on the first include that is not it, regardless of whether or not it is actually there later in the file or before, which will always be any other include file.
What you should actually do is gather all of the include lines in an Array, then search for the file matching <stdint.h> only adding it if it isn't contained in the complete list.
Here is a way to do it:
open(my $FILE, '<', $input) or die $!;
my #lines = <$FILE>;
my $flag = 0;
my $pos = 0;
my $insert_pos = 1; #add stdin even if there're no other include
foreach(#lines) {
$pos++;
if (/#include/){
$insert_pos = $pos;
if (/#include <stdint.h>/) {
$insert_pos = 0;
last;
}
}
}
if ($insert_pos) {
splice #lines, $insert_pos, 0, "#include <stdint.h>"."\n";
}
This is an awful thing to be doing to a C project.
What you have coded adds #include <stdint.h> right after the first #include line, and has no effect on files that don't #include anything.
However, if you want to "edit" a file using Perl, then you should use Tie::File
The code in your question would look like this
use strict;
use warnings;
use Tie::File;
my ($input) = #ARGV;
tie my #c_file, 'Tie::File', $input or die qq{Unable to open C file "$input": $!};
for my $i (0 .. $#c_file) {
next unless $c_file[$i] =~ /#include/;
splice #c_file, $i, 0, '#include <stdint.h>';
last;
}
I'm beginning to learn perl and I'm writing a simple bubble sort using regular expressions. However, I can't get it to sort properly (alphabetically, delimiting by whitespace). It just ends up returning the same string. Can someone help? I'm sure it's something really simple. Thanks:
#!/usr/bin/perl
use warnings;
use strict;
my $document=<<EOF;
This is the beginning of my text...#more text here;
EOF
my $continue = 1;
my $swaps = 0;
my $currentWordNumber = 0;
while($continue)
{
$document =~ m#^(\w+\s+){$currentWordNumber}#g;
if($document =~ m#\G(\w+)(\s+)(\w+)#)
{
if($3 lt $1)
{
$document =~ s#\G(\w+)(\s+)(\w+)#$3$2$1#;
$swaps++;
}
else
{
pos($document) = 0;
}
$currentWordNumber++;
}
else
{
$continue = 0 if ($swaps == 0);
$swaps = 0;
$currentWordNumber = 0;
}
}
print $document;
SOLVED: I figured out the problem. I wasn't taking into account punctuation after a word.
If you just want to sort all the words, you don't have to use regular expressions... Simply splitting up the text by newlines and white spaces should be much faster:
sub bsort {
my #x = #_;
for my $i (0..$#x) {
for my $j (0..$i) {
#x[$i, $j] = #x[$j, $i] if $x[$i] lt $x[$j];
}
}
return #x;
}
print join (" ", bsort(split(/\s+/, $document)));
In the perl , how to read the contents between two marks. Source data like this
START_HEAD
ddd
END_HEAD
START_DATA
eee|234|ebf
qqq| |ff
END_DATA
--Generate at 2011:23:34
then I only want to get data between "START_DATA" and "END_DATA". How to do this ?
sub readFile(){
open(FILE, "<datasource.txt") or die "file is not found";
while(<FILE>){
if(/START_DATA/){
record(\*FILE);#start record;
}
}
}
sub record($){
my $fileHandle = $_[0];
while(<fileHandle>){
print $_."\n";
if(/END_DATA/) return ;
}
}
I write this code, it doesn't work. do you know why ?
Thanks
Thanks
You can use the range operator:
perl -ne 'print if /START_DATA/ .. /END_DATA/'
The output will include the *_DATA lines, too, but it should not be so hard to get rid of them.
Besides a few typos, your code is not too far off. Had you used
use strict;
use warnings;
You might have figured it out yourself. Here's what I found:
Don't use prototypes if you do not need them, or know what they do.
Normal sub declaration is sub my_function (prototype) {, but you can leave out the prototype and just use sub my_function {.
while (<fileHandle>) { is missing the $ sign to denote that it is
a variable (scalar) and not a global. Should be $fileHandle.
print $_."\n"; will add an extra newline. Just print; will do
what you expect.
if(/END_DATA/) return; is a syntax error. Brackets are not optional
in perl in this case. Unless you reverse the statement.
Use either:
return if (/END_DATA/);
or
if (/END_DATA/) { return }
Below is the cleaned up version. I commented out your open() while testing, so this would be a functional code example.
use strict;
use warnings;
readFile();
sub readFile {
#open(FILE, "<datasource.txt") or die "file is not found";
while(<DATA>) {
if(/START_DATA/) {
recordx(\*DATA); #start record;
}
}
}
sub recordx {
my $fileHandle = $_[0];
while(<$fileHandle>) {
print;
if (/END_DATA/) { return }
}
}
__DATA__
START_HEAD
ddd
END_HEAD
START_DATA
eee|234|ebf
qqq| |ff
END_DATA
--Generate at 2011:23:34
This is a pretty simple thing to do with regular expressions, just use the /s or /m (single line or multiple line) flags - /s allows the . operator to match newlines, so you can do /start_data(.+)end_data/is.