Loop over an array with index and element in the array

Perl looping of an array with index as well as the item stored in variables,


 /tmp$ cat loop_with_index.pl 
my @arr=(1,2,3,4);
while (my ($i, $x) = each(@arr)) {
    print "$i: $x\n";
}

 /tmp$ perl loop_with_index.pl 
0: 1
1: 2
2: 3
3: 4

Comments

Post a Comment

Popular posts from this blog

Multiple repeat error when the regex has multiple wildcards in python re module

When the regex being compiled in python which has multiple wild cards like plus or asterisks sequentially repeated, you will need to escape or else run into "multiple repeat error". This can happen with any of re module methods like search and sub etc, where the regex is compiled. > > > import re > > > re . compile ( " r++ " ) Traceback ( most recent call last ) : File " <stdin> " , line 1 , in < module > File " /usr/lib/python2.7/re.py " , line 190 , in compile return _compile ( pattern , flags ) File " /usr/lib/python2.7/re.py " , line 242 , in _compile raise error , v # invalid expression sre_constants . error : multiple repeat > > > re . compile ( " r** " ) Traceback ( most recent call last ) : File " <stdin> " , line 1 , in < module > File " /usr/lib/python2.7/re.py " , line 190 , in compile return _
Read more

Weakref proxy is for instance only ...

Proxy cannot be created for basic datatypes like list, dict, str and int. Proxy can be create for class instances only. Also proxy cannot be created for proxy of another instance. >>> import weakref >>> a = 'str' >>> b = weakref.proxy(a) Traceback (most recent call last):   File "<stdin>", line 1, in <module> TypeError: cannot create weak reference to 'str' object >>> a = 1 >>> b = weakref.proxy(a) Traceback (most recent call last):   File "<stdin>", line 1, in <module> TypeError: cannot create weak reference to 'int' object >>> a = [] >>> b = weakref.proxy(a) Traceback (most recent call last):   File "<stdin>", line 1, in <module> TypeError: cannot create weak reference to 'list' object >>> a = {} >>> b = weakref.proxy(a) Traceback (most recent call last):   File "<stdin>",
Read more

To speed up accessing files on nfs shares on a ubuntu machine ...

To enable nfs caching on ubuntu, sudo apt-get install cachefilesd sudo sed -i 's/nfs rw/nfs fsc,rw/' /etc/fstab service restart cachefilesd To use tmpfs instead of disk cache use this after making sure the runner has atleast 12G of memory, mount | grep fscache || mount -t tmpfs -o size=8192m tmpfs /fscache ls /fscache/disk0 || dd if=/dev/zero of=/fscache/disk0 bs=1M count=8191 sleep 15 ls /fscache/disk0 && echo 'y' | mkfs.ext4 /fscache/disk0 mount /fscache/disk0 /var/cache/fscache -t ext4 service cachefilesd restart
Read more