前言

在用sprintf()格式化輸出時，發現formatSpec可以是單引號建立的字串陣列，也可以是string(‘str’)建立的string。所以產生了疑惑，這兩者有什麼區別，各適用在什麼場合

官方文件

Character arrays and string arrays provide storage for text data in MATLAB®.

    A character array is a sequence of characters, just as a numeric array is a sequence of numbers. A typical use is to
 
 store short pieces of text as character vectors, such as c = 'Hello World'.

    A string array is a container for pieces of text. String arrays provide a set of functions for working with text as data. Starting in R2017a, you can create strings using double quotes, such as str = "Greetings friend". To convert
 
 data to string arrays, use the string function.

程式碼

str=sprintf('pi = %.5f',pi);  %輸出型別為char
str1=sprintf(string('pi = %.5f'),pi);    %輸出型別為string

輸出結果：

%測試字串陣列
>> class(str)
ans =
char

>> str(1)
ans =
p

>> size(str)
ans =
     1    12

%測試string
>> class(str1)
ans =
string
 


>> size(str1)
ans =
     1     1

>> str1(1)
ans = 
  string
    "pi = 3.14159"

總結

由文件中可看出：
1. 字串陣列就相當於資料型別為char的矩陣（向量）。用單引號建立。可以索引。
2. string相當於一個類。用string()函式建立例項物件。所以有一些函式可以對string進行操作。size為1*1。