“String - String()”的版本间的差异

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Constructs an instance of the String class. There are multiple versions that construct Strings from different data types (i.e. format them as sequences of characters), including:  
 
Constructs an instance of the String class. There are multiple versions that construct Strings from different data types (i.e. format them as sequences of characters), including:  
  
  -  a constant string of characters, in double quotes (i.e. a char array)
+
-  a constant string of characters, in double quotes (i.e. a char array)
  -  a single constant character, in single quotes
+
-  a single constant character, in single quotes
  -  another instance of the String object
+
-  another instance of the String object
  -  a constant integer or long integer
+
-  a constant integer or long integer
  -  a constant integer or long integer, using a specified base
+
-  a constant integer or long integer, using a specified base
  -  an integer or long integer variable
+
-  an integer or long integer variable
  -  an integer or long integer variable, using a specified base
+
-  an integer or long integer variable, using a specified base
  -  a float or double, using a specified decimal palces  
+
-  a float or double, using a specified decimal palces  
  
 
Constructing a String from a number results in a string that contains the ASCII representation of that number. The default is base ten, so  
 
Constructing a String from a number results in a string that contains the ASCII representation of that number. The default is base ten, so  
 
+
<pre style="color:dimgray">
 +
String thisString = String(13);
 +
</pre>
  
 
gives you the String "13". You can use other bases, however. For example,  
 
gives you the String "13". You can use other bases, however. For example,  
  
 
+
<pre style="color:dimgray">
 +
String thisString = String(13, HEX);
 +
</pre>
  
 
gives you the String "D", which is the hexadecimal representation of the decimal value 13. Or if you prefer binary,  
 
gives you the String "D", which is the hexadecimal representation of the decimal value 13. Or if you prefer binary,  
  
 +
<pre style="color:dimgray">
 +
String thisString = String(13, BIN);
 +
</pre>
  
 
gives you the String "1101", which is the binary representation of 13.  
 
gives you the String "1101", which is the binary representation of 13.  
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<font color="orange" size="+1">'''示例'''</font>
 
<font color="orange" size="+1">'''示例'''</font>
 
  
 
All of the following are valid declarations for Strings.  
 
All of the following are valid declarations for Strings.  
 
  
 
<pre style="color:dimgray">
 
<pre style="color:dimgray">
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String stringOne =  String(millis(), DEC);                        // using a long and a base
 
String stringOne =  String(millis(), DEC);                        // using a long and a base
 
String stringOne =  String(5.698, 3);                                // using a float and the decimal places
 
String stringOne =  String(5.698, 3);                                // using a float and the decimal places
 
 
</pre>
 
</pre>
  

2015年7月27日 (一) 16:56的最后版本

String

String()


描述

Constructs an instance of the String class. There are multiple versions that construct Strings from different data types (i.e. format them as sequences of characters), including:

-  a constant string of characters, in double quotes (i.e. a char array)
-  a single constant character, in single quotes
-  another instance of the String object
-  a constant integer or long integer
-  a constant integer or long integer, using a specified base
-  an integer or long integer variable
-  an integer or long integer variable, using a specified base
-  a float or double, using a specified decimal palces 

Constructing a String from a number results in a string that contains the ASCII representation of that number. The default is base ten, so

String thisString = String(13);

gives you the String "13". You can use other bases, however. For example,

String thisString = String(13, HEX);

gives you the String "D", which is the hexadecimal representation of the decimal value 13. Or if you prefer binary,

String thisString = String(13, BIN);

gives you the String "1101", which is the binary representation of 13.


语法

String(val) String(val, base) String(val, decimalPlaces)


参数

val: a variable to format as a String - string, char, byte, int, long, unsigned int, unsigned long, float, double base (optional) - the base in which to format an integral value decimalPlaces (only if val is float or double) - the desired decimal places


返回值

an instance of the String class


示例

All of the following are valid declarations for Strings.

String stringOne = "Hello String";                                     // using a constant String
String stringOne =  String('a');                                          // converting a constant char into a String
String stringTwo =  String("This is a string");                 // converting a constant string into a String object
String stringOne =  String(stringTwo + " with more"); // concatenating two strings
String stringOne =  String(13);                                          // using a constant integer
String stringOne =  String(analogRead(0), DEC);          // using an int and a base
String stringOne =  String(45, HEX);                                // using an int and a base (hexadecimal)
String stringOne =  String(255, BIN);                               // using an int and a base (binary)
String stringOne =  String(millis(), DEC);                        // using a long and a base
String stringOne =  String(5.698, 3);                                // using a float and the decimal places

返回String

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