auto-increment alphanumeric php , javascript - php

Question

I want to make an auto-increment alphanumeric and this is just for output
if i press a button , there is an output AA001 and then i press a button again there is an output AA002

Answer 1

This doesn't use any 'clever' tricks but is shorter and easier to understand and tweak. It also uses numbers so it doesn't grow the length of the string as quickly. It increments from 0-9 then a-z, but it is intended that you should feed in 'a' to start with. Output always starts with an alphabet character, as long as your input also starts with an alphabet character, so it can be used as PHP variable names
var nextVarName = function(str) {
// Position of char to change.
var change = str.length - 1;
// The value of that char.
var change_char = str[change];
// Number of zeros to append when flipping.
var zeros = 0;
// Iterate backwards while there's a z (flipping).
while (change_char == 'z') {
// Increase the length of appended zeros
zeros++;
// Move the char to change back.
change_char = str[--change];
}
if (change_char == undefined) {
// Full flip - string increases in length.
str = 'a' + Array(str.length + 1).join("0");
} else {
// Normal increment with partial flip and 9->a handling.
str = str.substr(0, change)
+ (change_char == '9' ? 'a' : String.fromCharCode(str.charCodeAt(change) + 1))
+ Array(zeros + 1).join('0');
}
return str;
};
var vname = 'a';
for (var i = 0; i < 5; i++) {
vname = nextVarName(vname);
console.log(vname);
}
The results will be as follows:
z ---> a0
9z ---> a0 (unexpected input)
ab1zde ---> ab1zdf
abcdzz ---> abce00
zzzzz ---> a00000
abcyzz ---> abcz00
9000 ---> 9001 (unexpected input)
https://jsfiddle.net/e20kfvky/
The schedule of how many variables (that start with an alphabet char) are created of each length is as follows:
1: 26, 2: 936, 3: 33696, 4: 1213056 ... n: 36 ^ n - 10 * 36 ^ (n - 1)

Answer 2

The following code will generate a token that you can advance by one. It uses some small classes to make it modular. The function you attach to the button will call the function next on the token as shown in the very bottom.
//Element in a big token
function Increment(startval, endval) {
this.start = startval.charCodeAt(0);
this.cur = this.start;
this.end = endval.charCodeAt(0);
//Returns the current value
this.get = function() {
if (this.cur <= this.end) {
return String.fromCharCode(this.cur);
} else {
return null;
}
}
//Advances the value we will show
this.next = function() {
this.cur += 1;
return this.get();
}
//Reset it to the beginning
this.reset = function() {
this.cur = this.start;
}
}
function Token() {
this.token = [
new Increment("A", "Z"),
new Increment("A", "Z"),
new Increment("0", "9"),
new Increment("0", "9"),
new Increment("0", "9")
];
this.get = function() {
return this.token.map(function(cur) {
return cur.get();
}).join("");
}
this.next = function() {
//From the back to the front
for (var i = this.token.length - 1; i >= 0; i--) {
if (this.token[i].next() == null) {
//If we exhausted all possible values, continue
this.token[i].reset();
} else {
//Until we advance one that has still values left
break;
}
}
return this.get();
}
}
//Now we are just showing off...
var a = new Token();
for (var i = 0; i < 15; i++) {
console.log(a.next());
}

Answer 3

const getNextAlphaString = function (str) {
"use strict";
str=str.toUpperCase();
let chars;
chars = str.split("");
const strLen = str.length;
let continueIncermenting = true;
for (let i = strLen - 1; i >= 0; i = i - 1) {
let asciiVal;
asciiVal = chars[i].charCodeAt(0);
if (isNaN(asciiVal)) {
return str;
}
if (continueIncermenting === true) {
if (asciiVal >= 48 && asciiVal < 57) {
chars[i] = String.fromCharCode(asciiVal + 1);
continueIncermenting = false;
break;
} else if (asciiVal == 57) {
chars[i] = '0';
continueIncermenting = true;
}
if (asciiVal >= 65 && asciiVal < 90) {
chars[i] = String.fromCharCode(asciiVal + 1);
continueIncermenting = false;
break;
} else if (asciiVal == 90) {
chars[i] = String.fromCharCode(65);
continueIncermenting = true;
}
} else {
if (asciiVal == 90) {
continueIncermenting = true;
chars[i] = String.fromCharCode(65);
}
if (asciiVal == 57) {
continueIncermenting = true;
chars[i] = '0';
}
}
}
if (continueIncermenting === true) {
let firstAcii = chars[0].charCodeAt(0);
if (isNaN(firstAcii)) {
return str;
}
if ((firstAcii >= 65 && firstAcii <= 90) || (firstAcii >= 97 && firstAcii <= 122)) {
return 'A' + chars.join('').toUpperCase();
}
if (firstAcii >= 48 && firstAcii <= 57) {
return '0' + chars.join('').toUpperCase();
}
}
return chars.join('').toUpperCase();
};
The results will be as follows:
ab1zde ---> AB1ZDF
abcdzz ---> ABCEAA
zzzzz ---> AAAAAA
abcyzz ---> ABCZAA
9000 ---> 9001