oracle - The use of double vertical bars in pl/sql -


i want find reverse string program. there many examples have found none explain happens inside loop:

declare ln_rev_input varchar2(50); ln_input varchar2(50):= '&input';  begin      in reverse 1..length(ln_input) loop          ln_rev_input := ln_rev_input||substr(ln_input, i, 1);      end loop;      dbms_output.put_line(ln_rev_input); end;

i don't understand line, use of '||' in program:

ln_rev_input := ln_rev_input||substr(ln_input, i, 1);

i know '||' used concatenate strings don't understand how ln_rev_input being assigned.

thanks

the oracle/plsql || operator allows concatenate 2 or more strings together.

what above code is reversing input string. lets pass string named oracle, starts end of string oracle, takes 1 character @ time using function substr(ln_input, i, 1) , concatenates character whatever value there in ln_rev_input variable.

when starts, ln_rev_input null , result of ln_rev_input := ln_rev_input||substr(ln_input, i, 1); e.

when goes next iteration, character l concatenated whatever value there inside variable ln_rev_input, e - piece of code like

ln_rev_input := 'e' || 'l';

which result in value of ln_rev_input changed el. goes on 6 times, length of string - found using length(ln_input) - , in end, value of ln_rev_input elcaro.


Comments

Post a Comment

Popular posts from this blog

python - Installing PyDev in eclipse is failed -

unable read repository @ http://pydev.sf.net/updates/content.xml. sun.security.validator.validatorexception: pkix path building failed: sun.security.provider.certpath.suncertpathbuilderexception: unable find valid certification path requested target i installing pydev in eclipse using python, doesn't install successfully. gives above error. happened? how solve error? i had error when trying install on laptop behind corporate firewall. couldn't tell setup of firewall, not sure of root cause. i got passed error installing pydev eclipse when out behind firewall. another way got around have eclipse on non-firewalled machine, install pydev eclipse, , copy whole eclipse directory non-firewalled machine firewalled machine. there better way, , way fix properly, didn't have time work out firewall doing. this on windows 7 machine (yeah know) not work *nix versions installed through package manager yum or apt.
Read more

PHP OOP-based login system -

lets building oop-based user authentication system, , incorporate following principles: direct injection, inheritance, encapsulation, polymorphism , single responsibility principle. my background in programming has relied on procedural programming, , thus, finding difficult put these practices correct use. assume have these classes: class config { public function set($key, $value); public function get($key, $default = null); } class user { public function __construct(pdo $dbh, $id = null); public function setprofile(profile $profile); } class auth { public function __construct(config $config); public function login($username, $password, $keeploggedin = true); public function isloggedin(); public function getloggedinuser(); public function logout(); public function register(array $data); } class session { public function start($sessionname = null); public function write($key, $value); public function read($key, $default =...
Read more

c# - Nested Internal Class with Readonly Hashtable throws Null ref exception.. on assignment -

in internal game class , have both a) defined nested internal gamertags class , b) defined gamertags[] _array variable. in internal gamertags class (the nested class, simplicity left out) have readonly hashtable . after initialization, still null ref exception when try assign value. i'm not changing pointer value only , need add initialization hastable? internal class gamertags { private readonly hashtable _privatereadonlyhashtable; private string _json; private string _hash; internal idictionary privatereadonlyhashtable { { return this._privatereadonlyhashtable; } } internal string hash { { this.ensurehash(); return this._hash; } } internal object this[string key] { { return this._privatereadonlyhashtable[k...
Read more