C语言 使用 printf 格式在 C 中打印等宽列
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Print equal-width columns in C using printf formatting
提问by Brian Brown
I would like to print columns using printf in C. I wrote this code:
我想在 C 中使用 printf 打印列。我写了这个代码：
#include <stdio.h>
void printme(char *txt1, char *txt2, char *txt3)
{
printf("TXT1: %9s TXT2 %9s TXT3 %9s\n", txt1, txt2, txt3);
}
int main()
{
printme("a","bbbbbbbeeeeebbbbb","e");
printme("aaaaaaaa","bbbbbbbbbbbb","abcde");
return 0;
}
It works but I have such output:
它有效，但我有这样的输出：
TXT1: a TXT2 bbbbbbbeeeeebbbbb TXT3 e
TXT1: aaaaaaaa TXT2 bbbbbbbbbbbb TXT3 abcde
So the columns are not equal-width. Basicly, I would like to make it like this, that no matter how long is text in my argument, my function would ALWAYS print out a nice formatted columns. The question is: how can I do this?
所以列不是等宽的。基本上，我想这样做，无论我的论点中的文本有多长，我的函数都会始终打印出一个漂亮的格式化列。问题是：我该怎么做？
By saing niceI meant that no matter how long text I pass to my printing function, it will always print out equal-width columns, for example:
说好的我的意思是无论我传递给打印功能的文本有多长，它都会打印出等宽的列，例如：
I have this output that looks like this:
我的输出如下所示：
a cd` fg ij
a cd fg ij
a cd fg ij
ab cd fg ij
ab cd fg i j
ab cd fg ij
ab cd fg ij
ab cde fgh ij
ab cde fgh ij
I want it to look like this (no matter how long my text arguments will be):
我希望它看起来像这样（无论我的文本参数有多长）：
a cd` fg ij
a cd fg ij
a cd fg ij
ab cd fg ij
ab cd fg ij
ab cd fg ij
ab cd fg ij
ab cde fgh ij
ab cde fgh ij
采纳答案by jh314
You can find the maximum length for txt1, txt2, and txt3, and then format it:
你可以找到的最大长度txt1，txt2和txt3，然后格式化：
// compute the max string length of txt1 inputs in advance
int s1 = strlen(firstTxt1);
if (s1 < strlen(secondTxt1)
s1 = strlen(secondTxt1);
...
printf("%.*s %.*s %.*s\n", s1, txt1, s2, txt2, s3, txt3);
回答by Michael Burr
If you want the strings to be truncated if they're larger than the column width, then you can just add a precision for the string format specification:
如果您希望字符串在大于列宽时被截断，那么您只需为字符串格式规范添加一个精度：
printf("TXT1: %9.9s TXT2 %9.9s TXT3 %9.9s\n", txt1, txt2, txt3);
With that printf(), the output of your example program looks like:
这样printf()，您的示例程序的输出如下所示：
TXT1: a TXT2 bbbbbbbee TXT3 e
TXT1: aaaaaaaa TXT2 bbbbbbbbb TXT3 abcde
回答by Mats Petersson
Unfortunately, there is no TRIVIAL method for doing this.
不幸的是，没有简单的方法可以做到这一点。
You could do a two-pass method - in main():
你可以做一个两遍的方法 - 在 main() 中：
char **data[] = { { "a","bbbbbbbeeeeebbbbb","e" },
{"aaaaaaaa","bbbbbbbbbbbb","abcde" } };
get_columwidths(data[0][0], data[0][1], data[0][2]);
get_columwidths(data[1][0], data[1][1], data[1][2]);
printme(data[0][0], data[0][1], data[0][2]);
printme(data[1][0], data[1][1], data[1][2]);
and then this:
然后这个：
int columnwidths[3];
void get_columwidths(const char *s1, const char *s2, const char *s3)
{
int len1 = strlen(s1);
int len2 = strlen(s2);
int len3 = strlen(s3);
if (columnwidths[0] < len1) columnwidths[0] = len1;
if (columnwidths[1] < len2) columnwidths[1] = len2;
if (columnwidths[2] < len3) columnwidths[2] = len3;
}
void printme(char *txt1, char *txt2, char *txt3)
{
printf("TXT1: %*s TXT2 %*s TXT3 %*s\n",
columnwidths[0], txt1, columnwidths[1], txt2, columnwidths[2], txt3);
}
回答by Paul
Take a look at my simple library, libtprint: https://github.com/wizzard/libtprintThe code is pretty simple, you should be able to understand how it works.
看看我的简单库libtprint：https://github.com/wizzard/libtprint代码很简单，你应该能够理解它是如何工作的。
Basically what you need is to play with the fields widths for each column and calculate alignment offsets.
基本上你需要的是处理每列的字段宽度并计算对齐偏移量。
Hope it helps !
希望能帮助到你 ！
