string 我正在尝试在 matlab 中显示变量名称和它们值的 num2str 表示
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I am trying to display variable names and num2str representations of their values in matlab
提问by cuabanana
I am trying to produce the following:The new values of x and y are -4 and 7, respectively, using the disp and num2str commands. I tried to do this disp('The new values of x and y are num2str(x) and num2str(y) respectively'), but it gave num2str instead of the appropriate values. What should I do?
我正在尝试生成以下内容：使用 disp 和 num2str 命令，x 和 y 的新值分别为 -4 和 7。我试图这样做 disp('x 和 y 的新值分别是 num2str(x) 和 num2str(y)')，但它给出了 num2str 而不是适当的值。我该怎么办？
回答by Eitan T
Like Colin mentioned, one option would be converting the numbers to strings using num2str, concatenating all strings manually and feeding the final result into disp. Unfortunately, it can get veryawkward and tedious, especially when you have a lot of numbers to print.
就像 Colin 提到的那样，一种选择是使用 将数字转换为字符串num2str，手动连接所有字符串并将最终结果输入disp. 不幸的是，它会变得非常笨拙和乏味，尤其是当您要打印大量数字时。
Instead, you can harness the power of sprintf, which is very similar in MATLAB to its C programming language counterpart. This produces shorter, more elegant statements, for instance:
相反，您可以利用 的强大功能sprintf，这在 MATLAB 中与其 C 编程语言非常相似。这会产生更短、更优雅的语句，例如：
disp(sprintf('The new values of x and y are %d and %d respectively', x, y))
You can control how variables are displayed using the format specifiers. For instance, if xis not necessarily an integer, you can use %.4f, for example, instead of %d.
您可以使用格式说明符控制变量的显示方式。例如，如果x不一定是整数，则可以使用%.4f，例如，代替%d。
EDIT: like Jonas pointed out, you can also use fprintf(...)instead of disp(sprintf(...)).
编辑：就像乔纳斯指出的那样，您也可以使用fprintf(...)代替disp(sprintf(...)).
回答by Colin T Bowers
Try:
尝试：
disp(['The new values of x and y are ', num2str(x), ' and ', num2str(y), ', respectively']);
You can actually omit the commas too, but IMHO they make the code more readable.
您实际上也可以省略逗号，但恕我直言，它们使代码更具可读性。
By the way, what I've done here is concatenated 5 strings together to form one string, and then fed that single string into the dispfunction. Notice that I essentially concatenated the string using the same syntax as you might use with numerical matrices, ie [x, y, z]. The reason I can do this is that matlab stores character strings internally AS numeric row vectors, with each character denoting an element. Thus the above operation is essentially concatenating 5 numeric row vectors horizontally!
顺便说一下，我在这里所做的是将 5 个字符串连接在一起形成一个字符串，然后将该单个字符串输入到disp函数中。请注意，我基本上使用与数字矩阵相同的语法连接字符串，即[x, y, z]. 我可以这样做的原因是 matlab 在内部将字符串存储为数字行向量，每个字符表示一个元素。因此，上述操作本质上是水平连接 5 个数字行向量！
One further point: Your code failed because matlab treated your num2str(x) as a string and not as a function. After all, you might legitimately want to print "num2str(x)", rather than evaluate this using a function call. In my code, the first, third and fifth strings are defined as strings, while the second and fourth are functions which evaluate to strings.
还有一点：您的代码失败，因为 matlab 将您的 num2str(x) 视为字符串而不是函数。毕竟，您可能合情合理地想要打印“num2str(x)”，而不是使用函数调用来评估它。在我的代码中，第一个、第三个和第五个字符串被定义为字符串，而第二个和第四个是计算为字符串的函数。
