disp(fprintf())打印fprintf和字符数.为什么?

问题描述：

巧合的是，我发现disp(fprintf())打印出fprintf的字符串及其所包含的字符数.我知道disp()是多余的，但是出于纯粹的好奇心，我想知道为什么它打印字符数，因为这一天实际上可能会有所帮助.
例如

By coincidence I discovered, that disp(fprintf()) prints the string of fprintf plus the number of characters that it has. I know, that the disp() is reduntant, but just out of pure curiosity I want to know, why it prints the number of characters, since this might be actually helpful one day.
For example

disp(fprintf('Hi %i all of you',2))

产生

大家好，大家15个

Hi 2 all of you 15

答

问题中提到的特定行为的原因是对FILEprintf的调用

The reason for the specific behaviour mentioned in the question is the call to FILEprintf fprintf with a storage variable:

nbytes = fprintf(___)使用前面语法中的任何输入参数返回fprintf写入的字节数.

nbytes = fprintf(___) returns the number of bytes that fprintf writes, using any of the input arguments in the preceding syntaxes.

所以发生的情况是disp(fprintf(...))首先按照fprintf打印文本，但没有存储变量，但是disp仅看到fprintf的存储变量，它是字符串的字节数，因此输出.

So what happens is that disp(fprintf(...)) first prints the text as per fprintf without a storage variable, but disp sees only the storage variable of fprintf, which is the number of bytes of your string, hence the output.

此外，如果要显示字符串，则需要STRINGprintf: sprintf :

As an addition, if you want to display strings, you need STRINGprintf: sprintf:

disp(sprintf('Hi %i all of you',2))
Hi 2 all of you

文档向我展示的是sprintf仅用于字符串格式化，您可以将其用于将图形添加到文本，设置顺序文件名等，而fprintf则可以写入文本文件.

What the docs show me is that sprintf is exclusively used for string formatting, which you can use for adding text to a graph, setting up sequential file names etc, whilst fprintf writes to a text file.

str = sprintf(formatSpec,A1,...,An)按照列顺序按formatSpec格式化数组A1，...，An中的数据，并将结果返回到字符串str.

str = sprintf(formatSpec,A1,...,An) formats the data in arrays A1,...,An according to formatSpec in column order, and returns the results to string str.

fprintf(fileID,formatSpec,A1,...,An)按列顺序将formatSpec应用于数组A1，... An的所有元素，并将数据写入文本文件. fprintf使用对fopen的调用中指定的编码方案.

fprintf(fileID,formatSpec,A1,...,An) applies the formatSpec to all elements of arrays A1,...An in column order, and writes the data to a text file. fprintf uses the encoding scheme specified in the call to fopen.

fprintf(formatSpec,A1,...,An)格式化数据并在屏幕上显示结果.

fprintf(formatSpec,A1,...,An) formats data and displays the results on the screen.

用于在屏幕上显示文本，因此disp(sprintf())或fprintf是相等的，但是如果要将结果存储在字符串中，则必须使用sprintf，并且如果要将其写入文本文件，则必须使用fprintf.

For displaying text on screen therefore disp(sprintf()) or fprintf are equal, but if you want to store the results in a string you have to use sprintf and if you want to write it to a text file you have to use fprintf.

disp(fprintf())打印fprintf和字符数.为什么?

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