将数字转换为字母
Convert number to alphabet letter
我想将一个数字转换为其相应的字母。例如:
1 = A
2 = B
3 = C
这可以在javascript中完成而无需手动创建数组吗?在 php 中有一个 range() 函数可以自动创建数组。在javascript中有什么类似的东西吗?
是的,有Number#toString(36)
和调整。
var value = 10;
document.write((value + 9).toString(36).toUpperCase());
你可以简单地做到这一点,而无需使用数组String.fromCharCode(code)
因为字母有连续的代码。例如:String.fromCharCode(1+64)
给你"A",String.fromCharCode(2+64)
给你"B",依此类推。
下面的代码片段将字母表中的字符转换为数字系统
1 = A
2 = B
...
26 = Z
27 = AA
28 = AB
...
78 = BZ
79 = CA
80 = CB
var alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
var result = ""
function printToLetter(number){
var charIndex = number % alphabet.length
var quotient = number/alphabet.length
if(charIndex-1 == -1){
charIndex = alphabet.length
quotient--;
}
result = alphabet.charAt(charIndex-1) + result;
if(quotient>=1){
printToLetter(parseInt(quotient));
}else{
console.log(result)
result = ""
}
}
我创建了这个函数是为了在打印时保存字符,但不得不废弃它,因为我不想处理最终可能形成的不正确的单词
只需将字母索引从 0 (A) 增加到 25 (Z)
const letterIndex = 0
const letter = String.fromCharCode(letterIndex + 'A'.charCodeAt(0))
console.log(letter)
更新(5/2/22):在第二个项目中需要这段代码后,我决定增强以下答案并将其转换为一个名为 alphanumeric-encoder
的现成 NPM 库。如果您不想为此问题构建自己的解决方案,请查看库!
我构建了以下解决方案,作为对@esantos答案的增强。
第一个函数定义有效的查找编码字典。在这里,我使用了英文字母表的所有 26 个字母,但以下内容也可以正常工作:"ABCDEFG"
、"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
、"GFEDCBA"
。使用这些词典之一将导致将您的基数 10 转换为具有适当编码数字的基数dictionary.length
数。唯一的限制是字典中的每个字符都必须是唯一的。
function getDictionary() {
return validateDictionary("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
function validateDictionary(dictionary) {
for (let i = 0; i < dictionary.length; i++) {
if(dictionary.indexOf(dictionary[i]) !== dictionary.lastIndexOf(dictionary[i])) {
console.log('Error: The dictionary in use has at least one repeating symbol:', dictionary[i])
return undefined
}
}
return dictionary
}
}
我们现在可以使用这个字典来编码我们的基数 10。
function numberToEncodedLetter(number) {
//Takes any number and converts it into a base (dictionary length) letter combo. 0 corresponds to an empty string.
//It converts any numerical entry into a positive integer.
if (isNaN(number)) {return undefined}
number = Math.abs(Math.floor(number))
const dictionary = getDictionary()
let index = number % dictionary.length
let quotient = number / dictionary.length
let result
if (number <= dictionary.length) {return numToLetter(number)} //Number is within single digit bounds of our encoding letter alphabet
if (quotient >= 1) {
//This number was bigger than our dictionary, recursively perform this function until we're done
if (index === 0) {quotient--} //Accounts for the edge case of the last letter in the dictionary string
result = numberToEncodedLetter(quotient)
}
if (index === 0) {index = dictionary.length} //Accounts for the edge case of the final letter; avoids getting an empty string
return result + numToLetter(index)
function numToLetter(number) {
//Takes a letter between 0 and max letter length and returns the corresponding letter
if (number > dictionary.length || number < 0) {return undefined}
if (number === 0) {
return ''
} else {
return dictionary.slice(number - 1, number)
}
}
}
一组编码的字母很棒,但是如果我不能将其转换回以 10 为基数的数字,这对计算机来说就毫无用处。
function encodedLetterToNumber(encoded) {
//Takes any number encoded with the provided encode dictionary
const dictionary = getDictionary()
let result = 0
let index = 0
for (let i = 1; i <= encoded.length; i++) {
index = dictionary.search(encoded.slice(i - 1, i)) + 1
if (index === 0) {return undefined} //Attempted to find a letter that wasn't encoded in the dictionary
result = result + index * Math.pow(dictionary.length, (encoded.length - i))
}
return result
}
现在测试一下:
console.log(numberToEncodedLetter(4)) //D
console.log(numberToEncodedLetter(52)) //AZ
console.log(encodedLetterToNumber("BZ")) //78
console.log(encodedLetterToNumber("AAC")) //705
更新
您还可以使用此函数采用您拥有的短名称格式,并将其返回到基于索引的格式。
function shortNameToIndex(shortName) {
//Takes the short name (e.g. F6, AA47) and converts to base indecies ({6, 6}, {27, 47})
if (shortName.length < 2) {return undefined} //Must be at least one letter and one number
if (!isNaN(shortName.slice(0, 1))) {return undefined} //If first character isn't a letter, it's incorrectly formatted
let letterPart = ''
let numberPart= ''
let splitComplete = false
let index = 1
do {
const character = shortName.slice(index - 1, index)
if (!isNaN(character)) {splitComplete = true}
if (splitComplete && isNaN(character)) {
//More letters existed after the numbers. Invalid formatting.
return undefined
} else if (splitComplete && !isNaN(character)) {
//Number part
numberPart = numberPart.concat(character)
} else {
//Letter part
letterPart = letterPart.concat(character)
}
index++
} while (index <= shortName.length)
numberPart = parseInt(numberPart)
letterPart = encodedLetterToNumber(letterPart)
return {xIndex: numberPart, yIndex: letterPart}
}
有一个单行函数numAbbr
用于将数字转换为字符串,例如
1 => A
2 => B
...
26 => Z
27 => AA
28 => AB
...
702 => ZZ
703 => AAA
const numAbbr = num => num <= 0 ? '' : numAbbr(Math.floor((num - 1) / 26)) + String.fromCharCode((num - 1) % 26 + 65);
和相反的函数abbrNum
将AAA
等字符串转换为数字
const abbrNum = abbr => abbr.toUpperCase().split("").reduce((acc, val) => acc * 26 + val.charCodeAt(0) - 64, 0);
的代码答案真的过于复杂,因为它可以通过一个简单的循环来实现
function colToLetter(number){
let result = '';
// number = number - 1; // If starting from 1
do {
const letter = String.fromCharCode(65 + (number % 26));
result = letter + result;
number = Math.floor(number / 26) - 1;
} while (number >= 0)
return result;
}
console.log(colToLetter(0));
console.log(colToLetter(25));
console.log(colToLetter(26));
console.log(colToLetter(702));
console.log(colToLetter(728));
这提供了类似 excel 的编号
这可以帮助你
static readonly string[] Columns_Lettre = new[] { "A", "B", "C"};
public static string IndexToColumn(int index)
{
if (index <= 0)
throw new IndexOutOfRangeException("index must be a positive number");
if (index < 4)
return Columns_Lettre[index - 1];
else
return index.ToString();
}
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