JavaScript 有 strcmp() 吗？

Question

有人可以帮我验证一下吗？ JavaScript 没有 strcmp() 版本，因此您必须写出如下内容：

 ( str1 < str2 ) ? 
            -1 : 
             ( str1 > str2 ? 1 : 0 );

Answer 1

正如你所指出的，Javascript 没有它。

快速搜索得出：

function strcmp ( str1, str2 ) {
    // http://kevin.vanzonneveld.net
    // +   original by: Waldo Malqui Silva
    // +      input by: Steve Hilder
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +    revised by: gorthaur
    // *     example 1: strcmp( 'waldo', 'owald' );
    // *     returns 1: 1
    // *     example 2: strcmp( 'owald', 'waldo' );
    // *     returns 2: -1

    return ( ( str1 == str2 ) ? 0 : ( ( str1 > str2 ) ? 1 : -1 ) );
}

来自 http://kevin.vanzonneveld.net/techblog/article/ javascript_equivalent_for_phps_strcmp/

当然，如果需要，您可以只添加 localeCompare：

if (typeof(String.prototype.localeCompare) === 'undefined') {
    String.prototype.localeCompare = function(str, locale, options) {
        return ((this == str) ? 0 : ((this > str) ? 1 : -1));
    };
}

并在任何地方使用 str1.localeCompare(str2)，而不必担心本地浏览器是否已附带它。 唯一的问题是您必须添加对 区域设置和选项（如果您关心的话）。

Answer 2

localeCompare() 很慢，所以如果你不关心“正确”的顺序对于非英文字符串，请尝试原始方法或看起来更简洁的方法：

str1 < str2 ? -1 : +(str1 > str2)

这比我的机器上的 localeCompare() 快一个数量级。

+ 确保答案始终是数字而不是布尔值。

Answer 3

var strcmp = new Intl.Collator(undefined, {numeric:true, sensitivity:'base'}).compare;

用法：strcmp(string1, string2)

结果：1 表示 string1 更大，0 表示相等，-1意味着 string2 更大。

这比 String.prototype.localeCompare 具有更高的性能，

而且 numeric:true 使其可以进行逻辑数字比较

Answer 4

来自这篇如何在 JavaScript 中检查两个字符串是否相等文章：

1. 一般情况，如果您的字符串仅包含 ASCII 字符，则可以使用 === 运算符来检查它们是否相等。
2. 但是，当您的字符串包含包含组合字符的字符（例如 e + ◌́ = é）时，您首先要对它们进行规范化，然后再比较相等性，如下所示 -
   s1.normalize() === s2.normalize()

Answer 5

所以我陷入了这个兔子洞并编写了一些测试来建立直觉，结果很奇怪。
tldr 看起来像 localeCompare 执行小写
相等运算符则不然。 这会导致“ff”>=“ZZ”，但区域设置比较返回-1，因为“ff”<=“zz”

为了获得最佳结果，请在浏览器控制台中查看代码日志ctrl + shift + i

第二个片段，它会隐藏手动测试所以你会看到一些随机的。

主页这对某人有帮助

function stringBench(n, bench, min = 10, len = 10, logDif = false) {
  function makeid(length) {
    var result = '';
    var characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    var charactersLength = characters.length;
    for (var i = 0; i < length; i++) {
      result += characters.charAt(Math.floor(Math.random() *
        charactersLength));
    }
    return result;

  }

  var a = [];
  var b = [];
  var pool = {};
  let rle = [];
  let rlc = [];

  let now;
  for (let i = 0; i < n; i++) {
    pool[i] = (makeid(min + Math.floor(Math.random() *
      len))); //10-20ish

  }
  for (let i = 0; i < bench; i++) {
    a[i] = (Math.floor(Math.random() * n));
    b[i] = (Math.floor(Math.random() * n));
  }

  console.log("now testin le vs lc on a pool of", n, " with this many samples ", bench);
  now = Date.now();
  for (let i = 0; i < bench; i++) {
    rlc[i] = pool[a[i]].localeCompare(pool[b[i]]);
  }
  let lcDelta = Date.now() - now;
  console.log("Performed ", bench, "lc localeCompare in ", lcDelta);


  now = Date.now();
  for (let i = 0; i < bench; i++) {
    rle[i] = pool[a[i]] <= pool[b[i]];
  }
  let leDelta = Date.now() - now;
  console.log("Performed ", bench, "le (<=) compares in ", leDelta)

  for (let i = 0; i < n; i++) {
    pool[i] = (makeid(min + Math.floor(Math.random() *
      len))); //10-20ish

  }
  for (let i = 0; i < bench; i++) {
    a[i] = (Math.floor(Math.random() * n));
    b[i] = (Math.floor(Math.random() * n));
  }


  now = Date.now();
  for (let i = 0; i < bench; i++) {
    rle[i] = pool[a[i]] <= pool[b[i]];
  }
  let leDelta2 = Date.now() - now;
  console.log("Performed ", bench, "le (<=) compares in ", leDelta2)

  now = Date.now();
  for (let i = 0; i < bench; i++) {
    rlc[i] = pool[a[i]].localeCompare(pool[b[i]]);
  }
  let lcDelta2 = Date.now() - now;
  console.log("Performed ", bench, "lc localeCompare in ", lcDelta2);

  function testCmp(a, b, log = true) {
    let le = a <= b;
    let ge = a >= b;
    let lc = a.localeCompare(b);
    let l = a < b;
    let g = a > b;
    if (le && ge) console.assert(lc == 0, 'le && ge -> == -> lc == 0,')
    if (le) console.assert(lc <= 0, 'le-> lc <= 0')
    if (ge) console.assert(lc >= 0, 'ge-> lc >= 0')
    if (l) console.assert(lc < 0, 'l=>lc < 0')
    if (g) console.assert(lc > 0, 'g-> lc > 0')
    if (!log) return;
    console.log(`Compare:  ${a} le ${b} `, a <= b);
    console.log(`Compare:  ${a} ge ${b}`, a >= b);
    console.log(`Compare: ${a} lc ${b}`, a.localeCompare(b));
  }

  let c = 0
  for (let i = 0; i < bench; i++) {
    if (rle[i] != rlc[i] <= 0) {
      c++;
      testCmp(pool[a[i]], pool[b[i]], true);
      console.warn(pool[a[i]], ' le != lc <= 0 ', pool[b[i]]);

    }


    // rlc[i] = pool[a[i]].localeCompare(pool[b[i]]);
  }
  console.warn(' le != lc  out of bench, num diffs: ', c);


  testCmp('ff', 'ff')
  testCmp('ff', 'fa')
  testCmp('ff', 'fz')
  testCmp('ff', 'fff')
  testCmp('ff', 'ffa')
  testCmp('ff', 'ffz')
  testCmp('ff', 'a')
  testCmp('ff', 'z')
  testCmp('ff', 'f')
  testCmp('ff', 'zff')
  testCmp('ff', 'aff')
  testCmp('ff', 'ZZ')
  testCmp('ff', 'AA')
  testCmp('FF', 'ZZ')
  testCmp('FF', 'ff')
  testCmp('FF', 'AA')
  testCmp('ff', 'ZZZ')

  console.log("Dif le - lc = ", leDelta2 - lcDelta2);

  console.log("avg le ms/Mops = ", (leDelta + leDelta2) / (bench / 1000000));
  console.log("avg lc ms/Mops = ", (lcDelta + lcDelta2) / (bench / 1000000));


  console.log("Dif  - lc = ", leDelta2 - lcDelta2);

};
stringBench(1000, 5000, 1, 3, true);
// stringBench(1000000, 1000000);//nothing is equire
// stringBench(1000, 100000000);
// stringBench(1000000, 100000000, 3, 5);
// stringBench(1000000, 100000000, 15, 20);

function stringBench(n, bench, min = 10, len = 10, logDif = false) {
  function makeid(length) {
    var result = '';
    var characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    var charactersLength = characters.length;
    for (var i = 0; i < length; i++) {
      result += characters.charAt(Math.floor(Math.random() *
        charactersLength));
    }
    return result;


  }

  var a = [];
  var b = [];
  var pool = {};
  let rle = [];
  let rlc = [];

  let now;
  for (let i = 0; i < n; i++) {
    pool[i] = (makeid(min + Math.floor(Math.random() *
      len))); //10-20ish

  }
  for (let i = 0; i < bench; i++) {
    a[i] = (Math.floor(Math.random() * n));
    b[i] = (Math.floor(Math.random() * n));
  }

  console.log("now testin le vs lc on a pool of", n, " with this many samples ", bench);
  now = Date.now();
  for (let i = 0; i < bench; i++) {
    rlc[i] = pool[a[i]].localeCompare(pool[b[i]]);
  }
  let lcDelta = Date.now() - now;
  console.log("Performed ", bench, "lc localeCompare in ", lcDelta);


  now = Date.now();
  for (let i = 0; i < bench; i++) {
    rle[i] = pool[a[i]] <= pool[b[i]];
  }
  let leDelta = Date.now() - now;
  console.log("Performed ", bench, "le (<=) compares in ", leDelta)

  for (let i = 0; i < n; i++) {
    pool[i] = (makeid(min + Math.floor(Math.random() *
      len))); //10-20ish

  }
  for (let i = 0; i < bench; i++) {
    a[i] = (Math.floor(Math.random() * n));
    b[i] = (Math.floor(Math.random() * n));
  }


  now = Date.now();
  for (let i = 0; i < bench; i++) {
    rle[i] = pool[a[i]] <= pool[b[i]];
  }
  let leDelta2 = Date.now() - now;
  console.log("Performed ", bench, "le (<=) compares in ", leDelta2)

  now = Date.now();
  for (let i = 0; i < bench; i++) {
    rlc[i] = pool[a[i]].localeCompare(pool[b[i]]);
  }
  let lcDelta2 = Date.now() - now;
  console.log("Performed ", bench, "lc localeCompare in ", lcDelta2);

  function testCmp(a, b, log = true) {
    let le = a <= b;
    let ge = a >= b;
    let lc = a.localeCompare(b);
    let l = a < b;
    let g = a > b;
    if (le && ge) console.assert(lc == 0, 'le && ge -> == -> lc == 0,')
    if (le) console.assert(lc <= 0, 'le-> lc <= 0')
    if (ge) console.assert(lc >= 0, 'ge-> lc >= 0')
    if (l) console.assert(lc < 0, 'l=>lc < 0')
    if (g) console.assert(lc > 0, 'g-> lc > 0')
    if (!log) return;
    console.log(`Compare:  ${a} le ${b} `, a <= b);
    console.log(`Compare:  ${a} ge ${b}`, a >= b);
    console.log(`Compare: ${a} lc ${b}`, a.localeCompare(b));
  }

  let c = 0
  for (let i = 0; i < bench; i++) {
    if (rle[i] != rlc[i] <= 0) {
      c++;
      testCmp(pool[a[i]], pool[b[i]], true);
      console.warn(pool[a[i]], ' le != lc <= 0 ', pool[b[i]]);

    }


    // rlc[i] = pool[a[i]].localeCompare(pool[b[i]]);
  }
  console.warn(' le != lc  out of bench, num diffs: ', c);



  testCmp('ff', 'fa')
  testCmp('ff', 'fz')
  testCmp('ff', 'ZZ')



  console.log("Dif le - lc = ", leDelta2 - lcDelta2);

  console.log("avg le ms/Mops = ", (leDelta + leDelta2) / (bench / 1000000));
  console.log("avg lc ms/Mops = ", (lcDelta + lcDelta2) / (bench / 1000000));







  console.log("Dif  - lc = ", leDelta2 - lcDelta2);


  // for (let i = 0; i < bench; i++) {
  //     rlc[i] != rle[i]
  //     pool[a[i]].localeCompare(pool[b[i]]);
  // }
  //
  // console.log(makeid(5));
};
stringBench(1000, 5000, 1, 3, true);
// stringBench(1000000, 1000000);//nothing is equire
// stringBench(1000, 100000000);
// stringBench(1000000, 100000000, 3, 5);
// stringBench(1000000, 100000000, 15, 20);

Answer 6

在我的测试中，这比对同一组随机选择的单词使用一对三元语句快大约 10%。

function strcmp( a, b ) {
    for( let i=0 ; i<Math.min( a.length, b.length ) ; i++ ) {
        const n = a.charCodeAt(i) - b.charCodeAt(i);
        if( n ) return  n && ( ( n>>31 ) || 1 );
    }
    const n = a.length - b.length;
    return  n && ( ( n>>31 ) || 1 );
}

Answer 7

怎么样：

String.prototype.strcmp = function(s) {
    if (this < s) return -1;
    if (this > s) return 1;
    return 0;
}

然后，将 s1 与 2 进行比较：

s1.strcmp(s2)

Answer 8

关于什么

str1.localeCompare(str2)