以下是软件版本号:
"1.0", "1.0.1", "2.0", "2.0.0.1", "2.0.1"
我怎么比较呢?
假设正确的顺序是:
"1.0", "1.0.1", "2.0", "2.0.0.1", "2.0.1"
想法很简单…
读第一个数字,然后,第二个,第三个…
但是我不能将版本号转换为浮点数…
你也可以像这样看到版本号:
"1.0.0.0", "1.0.1.0", "2.0.0.0", "2.0.0.1", "2.0.1.0"
这样可以更清楚地看到背后的想法。
但是,我怎样才能把它转换成计算机程序呢?
这里有一个面向对象的有趣方法:
function versionString(str) {
var parts = str.split('.');
this.product = parts.length > 0 ? parts[0] * 1 : 0;
this.major = parts.length > 1 ? parts[1] * 1 : 0;
this.minor = parts.length > 2 ? parts[2] * 1 : 0;
this.build = parts.length > 3 ? parts[3] * 1 : 0;
this.compareTo = function(vStr){
vStr = this._isVersionString(vStr) ? vStr : new versionString(vStr);
return this.compare(this, vStr);
};
this.toString = function(){
return this.product + "." + this.major + "." + this.minor + "." + this.build;
}
this.compare = function (str1, str2) {
var vs1 = this._isVersionString(str1) ? str1 : new versionString(str1);
var vs2 = this._isVersionString(str2) ? str2 : new versionString(str2);
if (this._compareNumbers(vs1.product, vs2.product) == 0) {
if (this._compareNumbers(vs1.major, vs2.major) == 0) {
if (this._compareNumbers(vs1.minor, vs2.minor) == 0) {
return this._compareNumbers(vs1.build, vs2.build);
} else {
return this._compareNumbers(vs1.minor, vs2.minor);
}
} else {
return this._compareNumbers(vs1.major, vs2.major);
}
} else {
return this._compareNumbers(vs1.product, vs2.product);
}
};
this._isVersionString = function (str) {
return str !== undefined && str.build !== undefined;
};
this._compareNumbers = function (n1, n2) {
if (n1 > n2) {
return 1;
} else if (n1 < n2) {
return -1;
} else {
return 0;
}
};
}
还有一些测试:
var v1 = new versionString("1.0");
var v2 = new versionString("1.0.1");
var v3 = new versionString("2.0");
var v4 = new versionString("2.0.0.1");
var v5 = new versionString("2.0.1");
alert(v1.compareTo("1.4.2"));
alert(v3.compareTo(v1));
alert(v5.compareTo(v4));
alert(v4.compareTo(v5));
alert(v5.compareTo(v5));
2017答:
v1 = '20.0.12';
v2 = '3.123.12';
compareVersions(v1,v2)
// return positive: v1 > v2, zero:v1 == v2, negative: v1 < v2
function compareVersions(v1, v2) {
v1= v1.split('.')
v2= v2.split('.')
var len = Math.max(v1.length,v2.length)
/*default is true*/
for( let i=0; i < len; i++)
v1 = Number(v1[i] || 0);
v2 = Number(v2[i] || 0);
if (v1 !== v2) return v1 - v2 ;
i++;
}
return 0;
}
最简单的现代浏览器代码:
function compareVersion2(ver1, ver2) {
ver1 = ver1.split('.').map( s => s.padStart(10) ).join('.');
ver2 = ver2.split('.').map( s => s.padStart(10) ).join('.');
return ver1 <= ver2;
}
这里的想法是比较数字,但以字符串的形式。为了使比较工作,两个字符串必须在相同的长度。所以:
"123" > "99"变成"123" > "099"
填充短数字“修复”比较
这里我用0填充每个部分,长度为10。然后使用简单的字符串比较来得到答案
例子:
var ver1 = '0.2.10', ver2=`0.10.2`
//become
ver1 = '0000000000.0000000002.0000000010'
ver2 = '0000000000.0000000010.0000000002'
// then it easy to see that
ver1 <= ver2 // true
下面是一个版本,它对版本字符串进行排序,而不分配任何子字符串或数组。由于它分配的对象更少,GC要做的工作也就更少。
有一对分配(允许重用getVersionPart方法),但是如果您对性能非常敏感,您可以扩展它以完全避免分配。
const compareVersionStrings : (a: string, b: string) => number = (a, b) =>
{
var ia = {s:a,i:0}, ib = {s:b,i:0};
while (true)
{
var na = getVersionPart(ia), nb = getVersionPart(ib);
if (na === null && nb === null)
return 0;
if (na === null)
return -1;
if (nb === null)
return 1;
if (na > nb)
return 1;
if (na < nb)
return -1;
}
};
const zeroCharCode = '0'.charCodeAt(0);
const getVersionPart = (a : {s:string, i:number}) =>
{
if (a.i >= a.s.length)
return null;
var n = 0;
while (a.i < a.s.length)
{
if (a.s[a.i] === '.')
{
a.i++;
break;
}
n *= 10;
n += a.s.charCodeAt(a.i) - zeroCharCode;
a.i++;
}
return n;
}
我也遇到过类似的问题,而且我已经为它创建了一个解决方案。你可以试一试。
如果等于则返回0,如果版本号大于则返回1,如果版本号小于则返回-1
function compareVersion(currentVersion, minVersion) {
let current = currentVersion.replace(/\./g," .").split(' ').map(x=>parseFloat(x,10))
let min = minVersion.replace(/\./g," .").split(' ').map(x=>parseFloat(x,10))
for(let i = 0; i < Math.max(current.length, min.length); i++) {
if((current[i] || 0) < (min[i] || 0)) {
return -1
} else if ((current[i] || 0) > (min[i] || 0)) {
return 1
}
}
return 0
}
console.log(compareVersion("81.0.1212.121","80.4.1121.121"));
console.log(compareVersion("81.0.1212.121","80.4.9921.121"));
console.log(compareVersion("80.0.1212.121","80.4.9921.121"));
console.log(compareVersion("4.4.0","4.4.1"));
console.log(compareVersion("5.24","5.2"));
console.log(compareVersion("4.1","4.1.2"));
console.log(compareVersion("4.1.2","4.1"));
console.log(compareVersion("4.4.4.4","4.4.4.4.4"));
console.log(compareVersion("4.4.4.4.4.4","4.4.4.4.4"));
console.log(compareVersion("0","1"));
console.log(compareVersion("1","1"));
console.log(compareVersion("1","1.0.00000.0000"));
console.log(compareVersion("","1"));
console.log(compareVersion("10.0.1","10.1"));