c - 如何用变量指定字段宽度？

Question

我想知道是否可以使用变量来指定字段宽度，例如:

float g = 123.4567;
int x = 3;
int y = 4;
printf("%(%d).(%d)f", x,y,g);
I want my output to be: "123.4567", basically the same as

printf("%3.4f");

我认为编译器不会读取当前格式，但也许还有另一种方式。

Answer 1

这是关于 C 的问题吗？我看到了 q 标签，但我不确定，因为你谈论的是编译器......

无论如何，在 C 中它是用 * 完成的:

* The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

.* The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

printf ("Width trick: %*d \n", 5, 10);
Width trick:    10

http://www.cplusplus.com/reference/cstdio/printf/