c - 在 C 中使用 printf 或 printstring 格式化文本

Question

我想从微 Controller 将文本打印到终端程序，如下所示:

printString("textline one here:            OK\n");
printString("textline two here that is longer:             OK\n");
printString("textline three here that is even  longer:             OK\n");

即使我决定更改文本行，如何使文本始终位于列中？为了避免它在终端程序的打印输出中看起来像这样:

textline one here:             OK
textline two here that is longer:              OK
textline three here that is even  longer:              OK

更像这样(无需在文本中添加额外的空格并在终端程序中仔细检查它如何查找我对任何文本所做的每个更改):

textline one here:                             OK
textline two here that is longer:              OK
textline three here that is even  longer:      OK

为此使用 printf 或 printstring 是否更容易？

Answer 1

而不是将文本的第一部分直接包含在您的 printf 中格式字符串，将其作为参数传递给 %s格式说明符。然后，您可以向其添加字段宽度以指定要打印的最小字符数以及 -标志告诉它左对齐。

例如，这段代码:

printf("%-50s %s\n", "textline one here:", "OK");
printf("%-50s %s\n", "textline two here that is longer:", "OK");
printf("%-50s %s\n", "textline three here that is even  longer:","OK");

打印:

textline one here:                                 OK
textline two here that is longer:                  OK
textline three here that is even  longer:          OK

另外，您可以使用 *而不是显式字段宽度将其作为参数传递。这样，如果您需要更改列宽，您只需在一个地方进行:

int width = 50;
printf("%-*s %s\n", width, "textline one here:", "OK");
printf("%-*s %s\n", width, "textline two here that is longer:", "OK");
printf("%-*s %s\n", width, "textline three here that is even  longer:","OK");