在打印值时用C分隔值的最佳/常见实践

I tried the search function but only found questions regarding reading in comma/space delimited files.

我尝试了搜索功能，但是只找到了有关在逗号/空格分隔的文件中读取的问题。

My question is however, how do you usually approach this. Say I have a list/array/... of values, like {1, 2, 3, 4} and want to print them with a delimiter.

然而，我的问题是，你通常是如何做到这一点的。假设我有一个列表/数组/…的值，如{1,2,3,4}，并希望使用分隔符打印它们。

The simplest version would be something like:

最简单的版本是:

#include <stdio.h>

int main(void)
{
     char list[] = {1, 2, 3, 4};
     unsigned int i;

     for (i = 0; i < 4; ++i)
     printf("%d, ", list[i]);

     return 0;
}

which will obviously print "1, 2, 3, 4, ". The problem I have with that is the comma and space character at the end.

很明显，它会打印"1 2 3 4 "我的问题是最后的逗号和空格。

Now I could do:

现在我能做的:

#include <stdio.h>

int main(void)
{
    char list[] = {1, 2, 3, 4};
    unsigned int i;

    for (i = 0; i < 4; ++i)
    {
        printf("%d", list[i]);
        if (i < 3)
            printf(", ");
    }

    return 0;
}

Bút that doesn't seem like the best way to do it. Can somebody point me into the right direction? Thanks

但这似乎不是最好的方法。谁能给我指出正确的方向吗?谢谢

PS: No, I don't usually hardcode values
PPS: No, I am not trying to write .csv files ;)

PS:不，我通常不会硬编码值PPS:不，我不是在写。csv文件;)

7 个解决方案

#1

I use this idiom:

我用这个成语:

assert(n > 0);
printf("%d", list[0]);
for (i = 1; i < n; ++i)
     printf(", %d", list[i]);

Its one disadvantage is that it doesn't scale nicely for n == 0, like a simple loop. Alternatively, you can add protection against n == 0:

它的一个缺点是它不能很好地扩展到n = 0，就像一个简单的循环。另外，还可以添加n = 0的保护:

if (n > 0)
    printf("%d", list[0]);
for (i = 1; i < n; ++i)
     printf(", %d", list[i]);

#2

My standard technique for this is:

我对此的标准技术是:

const char *pad = "";
for (int i = 0; i < n; i++)
{
    printf("%s%d", pad, list[i]);
    pad = ", ";
}

Sometimes, the initial value of pad is a blank, or a colon blank, or whatever else works in context.

有时，pad的初始值是空的，或冒号空，或任何其他在上下文中工作的值。

#3

I picked up this format with the conditional operator from K&R2:

我用K&R2中的条件运算符找到了这个格式:

for (i = 0; i < n; i++)
    printf("%d%s", list[i], i+1 < n ? ", " : "\n");

#4

Well even thought there is already an accepted answer, nobody has come with the obvious one to my taste:

尽管已经有了一个公认的答案，但没有人能给出我最喜欢的答案:

#include <stdio.h>
int main(void) {
    unsigned list[] = {1, 2, 3, 4};
    unsigned const n = 4;
    if (n) for (unsigned i = 0; ; ++i) {
        printf("%d", list[i]);
        if (i >= n) break;
        printf(", ");
    }
    printf("\n");
    return 0;
}

#5

Use Michal Trybus's version or the reverse

使用米哈尔·特蕾布斯的版本或者相反的版本

for (i = 0; i < (n - 1); ++i) 
{
     printf("%d, ", list[i]);
}
printf("%d", list[n - 1]);

#6

for ( printf("%d",list[i=0]) ; i < n ; printf(", %d", list[++i]) ) ;

#7

Why not just another version while we're at it. Here's what I normally do

为什么不换一个版本呢?这是我通常做的

for (i=0;i<n;++i)
{
  if (i) printf(", ");
  printf("%d",list[i]);
}

#1