1、Python對(duì)象

Python使用對(duì)象模型來(lái)存儲(chǔ)數(shù)據(jù)，構(gòu)造任何類型的值都是一個(gè)對(duì)象。所有的對(duì)象都有三個(gè)特性：

• 身份，可通過(guò)內(nèi)建函數(shù)id()查看，這個(gè)值即該對(duì)象的內(nèi)存地址。
• 類型，可通過(guò)內(nèi)建函數(shù)type()查看。
• 值，對(duì)象表示的數(shù)據(jù)項(xiàng)。

<code class="hljs python has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>p = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>id(p) <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">31108092</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>type(p) <type <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'int'</span>> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>p <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>

2、標(biāo)準(zhǔn)類型

整型Integer，長(zhǎng)整型Long integer，浮點(diǎn)型float，復(fù)數(shù)型complex number，布爾型bool，字符串string，列表list，元組tuple，字典dictionary。

3、其他內(nèi)建類型

• type類型對(duì)象

  type類型本身就是一個(gè)對(duì)象，它的類型為‘type’。

<code class="hljs haskell has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">>>> <span class="hljs-typedef" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span><span class="hljs-container" style="box-sizing: border-box;">(1)</span></span> <<span class="hljs-typedef" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span> 'int'></span> >>> <span class="hljs-typedef" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span><span class="hljs-container" style="box-sizing: border-box;">(<span class="hljs-title" style="box-sizing: border-box;">type</span>(1)</span>)</span> <<span class="hljs-typedef" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span> '<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">type</span>'></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

• None——Python的Null對(duì)象

  Python有一個(gè)特殊的類型，稱作Null對(duì)象或者NoneType，它只有一個(gè)值：None，None的布爾值為False。

• 文件

• 集合
• 函數(shù)/方法
• 模塊
• 類

4、內(nèi)部類型

內(nèi)部類型我們一般不會(huì)過(guò)多關(guān)注與使用，了解一下即可。

• 代碼對(duì)象

  代碼對(duì)象是編譯過(guò)的Python源代碼片段，可執(zhí)行。可以通過(guò)內(nèi)建函數(shù)compile()得到代碼對(duì)象。代碼對(duì)象可以被exec命令或者內(nèi)建函數(shù)eval()執(zhí)行。

• 幀

• 跟蹤記錄對(duì)象

  程序出現(xiàn)異常退出時(shí)，一個(gè)包含針對(duì)異常的棧跟蹤信息的跟蹤記錄對(duì)象被創(chuàng)建：

<code class="hljs ruby has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">>>> pri<span class="hljs-constant" style="box-sizing: border-box;">Traceback</span> (most recent call last)<span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:</span><span class="hljs-constant" style="box-sizing: border-box;">File</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"<stdin>"</span>, line <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> <<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">module</span>></span><span class="hljs-constant" style="box-sizing: border-box;">NameError</span><span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">:</span> name <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'pri'</span> is <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">not</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">defined</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

• 切片對(duì)象

  當(dāng)使用Python的切片語(yǔ)法時(shí)，就會(huì)創(chuàng)建切片對(duì)象。

• 省略對(duì)象

  用于切片語(yǔ)法中，起記號(hào)作用。 如 str[::2]之類。

• Xrange對(duì)象

  調(diào)用內(nèi)建函數(shù)xrange()會(huì)生成一個(gè)XRange對(duì)象，xrange是range的兄弟版本，用于需要節(jié)省內(nèi)存 或 range無(wú)法完成的超大數(shù)據(jù)集場(chǎng)合。

5、標(biāo)準(zhǔn)類型操作符

• 對(duì)象值的比較

• 對(duì)象身份比較

  這個(gè)涉及到Python“引用計(jì)數(shù)”的相關(guān)知識(shí)，上一篇文章中有總結(jié)。Python還提供了is和is not操作符來(lái)測(cè)試兩個(gè)變量是否指向同一個(gè)對(duì)象。

<code class="hljs python has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>a = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>b =a <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>c = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>a == b <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">True</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>a <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">is</span> c <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">False</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>a <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">is</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">not</span> c <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">True</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>a <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">is</span> b <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">True</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

我們通過(guò)id也可以直接判斷它們是否指向同一對(duì)象：

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">>>> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span>(a),<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span>(b),<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span>(c) (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">31108224</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">31108224</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">31108212</span>)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

6、標(biāo)準(zhǔn)類型內(nèi)建函數(shù)

• cmp(obj1,obj2)

  obj1大于obj2則返回1，小于返回-1，等于返回0。

<code class="hljs python has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>a,b,c,d = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>cmp(b,a),cmp(b,c),cmp(b,d) (<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

• type(obj)

• str()、repr()、”操作符

  str()、repr()、”操作符都能夠以字符串的方式獲取對(duì)象的內(nèi)容。str()獲得的字符串可讀性好，repr()獲取的字符串通?？梢杂脕?lái)重新獲得該對(duì)象。

<code class="hljs python has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>str([<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>]) <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'[1, 2, 3]'</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span>repr([<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>]) <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'[1, 2, 3]'</span> <span class="hljs-prompt" style="color: rgb(0, 102, 102); box-sizing: border-box;">>>> </span><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'[1,2,3]'</span> <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'[1,2,3]'</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>

7、類型工廠函數(shù)

Python2.2統(tǒng)一了類和類型。原來(lái)所謂的內(nèi)建類型轉(zhuǎn)換函數(shù)像int()、type()、list()等都成了工廠函數(shù)，也就是說(shuō)他們看上去像函數(shù)，實(shí)質(zhì)上是類，當(dāng)調(diào)用它們時(shí)，實(shí)際上生成了該類型的一個(gè)實(shí)例，像工廠生成貨物一樣。

8、標(biāo)準(zhǔn)類型的分類

存儲(chǔ)模型，更新模型，訪問(wèn)模型。

9、Python不支持的類型

• char或byte
• 指針

• 整型

  Python中沒有像C語(yǔ)言那樣的int、short、long。當(dāng)你使用一個(gè)整型數(shù)值超出范圍時(shí)，python會(huì)自動(dòng)返回一個(gè)長(zhǎng)整型給你，python的長(zhǎng)整型表示的數(shù)值范圍很大。

• float vs double

  Python的浮點(diǎn)類型float實(shí)際上是C的double。浮點(diǎn)型總是不精確的，故Python還提供了Decimals模塊，它有任意精度，在處理金錢這類確定的值時(shí)，Decimals模塊很有用。

轉(zhuǎn)載于:https://www.cnblogs.com/csdndreamer/p/5490685.html

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