Hello All,
I am brand new to the UNIX world and so far and very intrigued and enjoy scripting. This is just a new language for me. I would really like assistance with the below request. Any help would be greatly appreciated!
I want to create a flat file in Vi that has a header field and... (0 Replies)
Hi All
I am reading a huge file of size 2GB atleast. I am reading each line and cutting certain columns and writing it to another file.
Here is the logic.
int main()
{
string u_line;
string Char_List;
string u_file;
int line_pos;
string temp_form_u_file;
... (10 Replies)
Hi!
Thank you for the help yesterday
This is the finished product
There is one more thing I would like to do to it but I’m not to certain
On how to proceed I would like to log all output to a log in order to
Be able to roll back
This script is meant to be used in repairing a... (4 Replies)
can anyone help to share the knowledge on linux os improvement?
1) os account
- use window AD authentication, such as ldap, but how to set /etc/passwd, where to put user home?
2) user account activity
- how to log os user activity
share the idea and what tools can do that...thx (5 Replies)
Heyas
I've been working on my project TUI (Text User Interface) for quite some time now, its a hobby project, so nothing i sit in front of 8hrs/day.
Since the only 'real' programming language i knw is Visual Basic, based upon early steps with MS-Batch files. When i 'joined' linux 3 years ago,... (7 Replies)
Hello Coders
Some time ago i was asking about python and bash performances, and i was told i could post the regarding code, and someone would kindly help to make it faster (if possible).
If you have noted, i'm on the way to finalize, finish, stable TUI - Text(ual) User Interface.
It is a... (6 Replies)
Below script is used to search numeric data from around 400 files in a folder. I have 300 such folders. Need help in performance improvement in the script.
Below Script searches 20 such folders ( 300 files in each folder) simultaneously. This increases cpu utilization upto 90% What changes... (3 Replies)
Hi,
another little question...
"sn" is an array whose elements can vary from about 55,000 to about 150,000 elements. Each element consists of an integer between 0-255, eg: ${sn} contain the value: 103 . For a decrypt-procedure I need scroll all the elements 4 or 5 times. Here is an example of... (15 Replies)
Hi guys and gals...
MacBook Pro.
OSX 10.13.2, default bash terminal.
I have a flat file 1920 bytes in size of whitespaces only. I need to put every single whitespace character into a bash array cell.
Below are two methods that work, but both are seriously ugly.
The first one requires that I... (7 Replies)
Hello,
For several of our scripts we are using awk to search patterns in files with data from other files. This works almost perfectly except that it takes ages to run on larger files. I am wondering if there is a way to speed up this process or have something else that is quicker with the... (15 Replies)
Discussion started by: SDohmen
15 Replies
LEARN ABOUT PHP
substr
SUBSTR(3) 1 SUBSTR(3)substr - Return part of a stringSYNOPSIS
string substr (string $string, int $start, [int $length])
DESCRIPTION
Returns the portion of $string specified by the $start and $length parameters.
PARAMETERS
o $string
- The input string. Must be one character or longer.
o $start
- If $start is non-negative, the returned string will start at the $start'th position in $string, counting from zero. For
instance, in the string ' abcdef', the character at position 0 is ' a', the character at position 2 is ' c', and so forth. If
$start is negative, the returned string will start at the $start'th character from the end of $string. If $string is less than or
equal to $start characters long, FALSE will be returned.
Example #1
Using a negative $start
<?php
$rest = substr("abcdef", -1); // returns "f"
$rest = substr("abcdef", -2); // returns "ef"
$rest = substr("abcdef", -3, 1); // returns "d"
?>
o $length
- If $length is given and is positive, the string returned will contain at most $length characters beginning from $start (depend-
ing on the length of $string). If $length is given and is negative, then that many characters will be omitted from the end of
$string (after the start position has been calculated when a $start is negative). If $start denotes the position of this trunca-
tion or beyond, false will be returned. If $length is given and is 0, FALSE or NULL, an empty string will be returned. If
$length is omitted, the substring starting from $start until the end of the string will be returned.
Example #2
Using a negative $length
<?php
$rest = substr("abcdef", 0, -1); // returns "abcde"
$rest = substr("abcdef", 2, -1); // returns "cde"
$rest = substr("abcdef", 4, -4); // returns false
$rest = substr("abcdef", -3, -1); // returns "de"
?>
RETURN VALUES
Returns the extracted part of $string; or FALSE on failure, or an empty string.
CHANGELOG
+--------------+---------------------------------------------------+
| Version | |
| | |
| | Description |
| | |
+--------------+---------------------------------------------------+
|5.2.2 - 5.2.6 | |
| | |
| | If the $start parameter indicates the position |
| | of a negative truncation or beyond, false is |
| | returned. Other versions get the string from |
| | start. |
| | |
+--------------+---------------------------------------------------+
EXAMPLES
Example #3
Basic substr(3) usage
<?php
echo substr('abcdef', 1); // bcdef
echo substr('abcdef', 1, 3); // bcd
echo substr('abcdef', 0, 4); // abcd
echo substr('abcdef', 0, 8); // abcdef
echo substr('abcdef', -1, 1); // f
// Accessing single characters in a string
// can also be achieved using "square brackets"
$string = 'abcdef';
echo $string[0]; // a
echo $string[3]; // d
echo $string[strlen($string)-1]; // f
?>
Example #4
substr(3) casting behaviour
<?php
class apple {
public function __toString() {
return "green";
}
}
echo "1) ".var_export(substr("pear", 0, 2), true).PHP_EOL;
echo "2) ".var_export(substr(54321, 0, 2), true).PHP_EOL;
echo "3) ".var_export(substr(new apple(), 0, 2), true).PHP_EOL;
echo "4) ".var_export(substr(true, 0, 1), true).PHP_EOL;
echo "5) ".var_export(substr(false, 0, 1), true).PHP_EOL;
echo "6) ".var_export(substr("", 0, 1), true).PHP_EOL;
echo "7) ".var_export(substr(1.2e3, 0, 4), true).PHP_EOL;
?>
The above example will output:
1) 'pe'
2) '54'
3) 'gr'
4) '1'
5) false
6) false
7) '1200'
ERRORS /EXCEPTIONS
Returns FALSE on error.
Example #5
<?php
var_dump(substr('a', 1)); // bool(false)
?>
SEE ALSO strrchr(3), substr_replace(3), preg_match(3), trim(3), mb_substr(3), wordwrap(3), String access and modification by character.
PHP Documentation Group SUBSTR(3)