blocks|key|1147197|text|单引号是字符(char)，双引号是以空结尾的字符串(char+*)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1147198|char+c+=+'x';
char+*s+=+"Hello+World";|code-block|syntax|javascript|1147199|entityMap^0|7|4|Q|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Single quotes are characters (<code>char</code>), double quotes are null-terminated strings (<code>char *</code>).

<pre><code>char c = 'x';
char *s = "Hello World";
</code></pre>

blocks|key|1147350|text|在C和C%2B%2B中，单引号标识单个字符，而双引号创建字符串文字。'a'是一个单字符文字，而"a"是一个包含'a'和空终止符(即2个字符的数组)的字符串文字。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1147351|在C%2B%2B中，字符文字的类型是char，但请注意，在C中，字符文字的类型是int，即在整数为32位的体系结构中，sizeof+'a'为4(而CHAR_BIT为8)，而sizeof(char)在任何地方都是1。|1147352|entityMap^0|U|3|17|3|1F|3|0|E|4|10|3|1J|A|2A|C|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|I|$]]

In C and in C++ single quotes identify a single character, while double quotes create a string literal. <code>'a'</code> is a single a character literal, while <code>"a"</code> is a string literal containing an <code>'a'</code> and a null terminator (that is a 2 char array).

In C++ the type of a character literal is <code>char</code>, but note that in C, the type of a character literal is <code>int</code>, that is <code>sizeof 'a'</code> is 4 in an architecture where ints are 32bit (and CHAR_BIT is 8), while <code>sizeof(char)</code> is 1 everywhere.

blocks|key|933013|text|在C中，诸如'a'之类的单引号表示字符常量，而"a"是一个字符数组，始终以\0字符结尾|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|933014|entityMap^0|6|3|N|3|11|2|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

In C, single-quotes such as <code>'a'</code> indicate character constants whereas <code>&quot;a&quot;</code> is an array of characters, always terminated with the <code>\0</code> character

blocks|key|933059|text|单引号用于单个字符。双引号用于字符串(字符数组)。如果您愿意，您可以使用单引号来构建字符串，一次一个字符。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|933060|char+myChar+++++=+'A';
char+myString[]+=+"Hello+Mum";
char+myOtherString[]+=+{+'H','e','l','l','o','\0'+};|code-block|syntax|javascript|933061|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Single quotes are for a single character. Double quotes are for a string (array of characters). You can use single quotes to build up a string one character at a time, if you like.

<pre><code>char myChar = 'A';
char myString[] = "Hello Mum";
char myOtherString[] = { 'H','e','l','l','o','\0' };
</code></pre>

blocks|key|1147484|text|使用带有单字符的单引号作为：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1147485|char+ch+=+'a';|code-block|syntax|javascript|1147486|这里的'a'是一个字符常量，等于字符a的ASCII值。|offset|length|style|CODE|1147487|字符串使用双引号，如下所示：|1147488|char+str[]+=+"foo";|1147489|这里的"foo"是一个字符串文字。|1147490|可以使用"a"，但不能使用'foo'|1147491|entityMap^0|0|0|3|3|K|5|0|0|0|3|5|0|4|3|E|4|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@$I|Z|J|10|K|L]|$I|11|J|12|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|14|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|15|8|@$I|16|J|17|K|L]]|9|@]|A|$]]|$1|S|3|T|5|6|7|18|8|@$I|19|J|1A|K|L]|$I|1B|J|1C|K|L]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|V|$]]

Use single quote with single char as:

<pre><code>char ch = 'a';
</code></pre>

here <code>'a'</code> is a char constant and is equal to the <code>ASCII</code> value of char a.

Use double quote with strings as:

<pre><code>char str[] = "foo";
</code></pre>

here <code>"foo"</code> is a string literal.

Its okay to use <code>"a"</code> but its not okay to use '<code>foo'</code>

blocks|key|1147530|text|单引号表示字符，双引号表示字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1147531|在Java中，也是一样的。|1147532|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Single quotes are denoting a char, double denote a string. 

In Java, it is also the same.

blocks|key|1147639|text|字符使用单引号，字符串使用双引号。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1147640|例如..。|1147641|+printf("%25c+\n",'a');
+printf("%25s","Hello+World");|code-block|syntax|javascript|1147642|输出|1147643|a++
Hello+World|1147644|如果反之亦然，对字符串使用单引号，对字符使用双引号，则结果如下：|1147645|++printf("%25c+\n","a");
++printf("%25s",'Hello+World');|1147646|输出：|1147647|用于第一行。你会得到一个无用的值或意外的值，或者你可能会得到如下的输出：|1147648|�|1147649|而对于第二个语句，您将什么也看不到。还有一件事，如果你在这之后有更多的语句，它们也不会给你任何结果。|1147650|注意:+PHP语言使您可以很容易地灵活地使用单引号和双引号。|1147651|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|15|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|16|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|17|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|18|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|19|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1A|8|@]|9|@]|A|$]]|$1|U|3|V|5|F|7|1B|8|@]|9|@]|A|$G|H]]|$1|W|3|X|5|6|7|1C|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1D|8|@]|9|@]|A|$]]|$1|10|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|11|$]]

A single quote is used for character, while double quotes are used for strings.
<h2>For example...</h2>
<pre><code> printf(&quot;%c \n&quot;,'a');
 printf(&quot;%s&quot;,&quot;Hello World&quot;);
</code></pre>
<h2>Output</h2>
<pre><code>a 
Hello World
</code></pre>
If you used these in vice versa case and used a single quote for string and double quotes for a character, this will be the result:
<pre><code> printf(&quot;%c \n&quot;,&quot;a&quot;);
 printf(&quot;%s&quot;,'Hello World');
</code></pre>
<h2>output :</h2>
For the first line. You will get a garbage value or unexpected value or you may get an output like this:
<pre><code>�
</code></pre>
While for the second statement, you will see nothing. One more thing, if you have more statements after this, they will also give you no result.
Note: PHP language gives you the flexibility to use single and double-quotes easily.

blocks|key|1147823|text|在C&+C%2B%2B中，单引号被称为字符('a')，而双引号被称为字符串("Hello")。不同的是，一个字符可以存储任何东西，除了一个字母/数字等等。一个字符串可以存储任何东西。但也要记住，'+1‘和1之间是有区别的。如果您键入cout<<’1‘<|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1147824|cout<<int('1')<<endl<<int(1);|code-block|syntax|javascript|1147825|
|1147826|这一次，第一行是48。当你把一个字符转换成一个整型时，它就会转换成它的ascii，而'1‘的ascii是48。同样，如果你这样做的话：|1147827|1147828|string+s="Hi";
s%2B=48;+//This+will+add+"1"+to+the+string
s%2B="1";+This+will+also+add+"1"+to+the+string|1147829|1147830|1147831|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|T|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|U|8|@]|9|@]|A|$]]|$1|K|3|H|5|6|7|V|8|@]|9|@]|A|$]]|$1|L|3|M|5|D|7|W|8|@]|9|@]|A|$E|F]]|$1|N|3|H|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|Q|$]]

In C &amp; C++ single quotes is known as a character ('a') whereas double quotes is know as a string (&quot;Hello&quot;). The difference is that a character can store anything but only one alphabet/number etc. A string can store anything.
But also remember that there is a difference between '1' and 1.
If you type
cout&lt;&lt;'1'&lt;&lt;endl&lt;&lt;1;
The output would be the same, but not in this case:
<pre><code>cout&lt;&lt;int('1')&lt;&lt;endl&lt;&lt;int(1);
</code></pre>
This time the first line would be 48. As when you convert a character to an int it converts to its ascii and the ascii for '1' is 48.
Same, if you do:
<pre><code>string s=&quot;Hi&quot;;
s+=48; //This will add &quot;1&quot; to the string
s+=&quot;1&quot;; This will also add &quot;1&quot; to the string
</code></pre>

blocks|key|933487|text|虽然我确信这不会回答最初的提问者的问题，但如果你最终像我一样在这里寻找文字整数中的单引号...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|933488|C%2B%2B14添加了添加single+quotes+(')+in+the+middle+of+number+literals的功能，以向数字添加一些可视化分组。|offset|length|style|CODE|933489|constexpr+int+oneBillion+=+1'000'000'000;
constexpr+int+binary+=+0b1010'0101;
constexpr+int+hex+=+0x12'34'5678;
constexpr+double+pi+=+3.1415926535'8979323846'2643383279'5028841971'6939937510;|code-block|syntax|javascript|933490|entityMap|0|LINK|mutability|MUTABLE|url|https://en.cppreference.com/w/cpp/language/integer_literal#Single_quote^0|0|P|1|A|1E|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@$D|W|E|X|F|G]]|9|@$D|Y|E|Z|1|10]]|A|$]]|$1|H|3|I|5|J|7|11|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

While I'm sure this doesn't answer what the original asker asked, in case you end up here looking for single quote in literal integers like I have...
C++14 added the ability to add <a href="https://en.cppreference.com/w/cpp/language/integer_literal#Single_quote" rel="nofollow noreferrer">single quotes (<code>'</code>) in the middle of number literals</a> to add some visual grouping to the numbers.
<pre><code>constexpr int oneBillion = 1'000'000'000;
constexpr int binary = 0b1010'0101;
constexpr int hex = 0x12'34'5678;
constexpr double pi = 3.1415926535'8979323846'2643383279'5028841971'6939937510;
</code></pre>

When should I use single quotes and double quotes in C or C++ programming?

问C或C++中的单引号与双引号
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