printf的右对齐一个括号数 [英] printf right align a bracketed number

问题描述

我正在写一个显示阵列中的所有信息的程序。它开始用括号中的数组索引（如 [2] ），他们必须是正确的互相对齐。

I'm writing a program that displays all the info in an array. It has to start with the array index in brackets (e.g. [2]) and they have to be right aligned with each other.

如果这只是数字，我知道，你可以这样做：

if it was just the number, I know that you can do:

printf("%-10d", index);

但把括号，将给予以下输出

but putting brackets around that would give the following output

[         1]
[         2]
...
[        10]
[        11]

当我真的希望它是：

         [1]
         [2]
...
        [10]
        [11]

我如何去这样做？

How do I go about doing this?

推荐答案

做它在两个步骤：先建立一个临时缓冲区不结盟字符串，然后打印字符串右对齐

Do it in two steps: first build a non-aligned string in a temporary buffer, then print the string right-aligned.

char buf[sizeof(index) * (CHAR_BITS + 2) / 3 + 4];
sprintf(buf, "[%d]", index);
printf("%-12s", buf);

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