如何在循环中使用 sscanf? [英] How to use sscanf in loops?

问题描述

有没有好办法用 sscanf 遍历字符串?

Is there a good way to loop over a string with sscanf?

假设我有一个看起来像这样的字符串:

Let's say I have a string that looks like this:

char line[] = "100 185 400 11 1000";

我想打印总和.我真正想写的是:

and I'd like to print the sum. What I'd really like to write is this:

int n, sum = 0;
while (1 == sscanf(line, " %d", &n)) {
  sum += n;
  line += <number of bytes consumed by sscanf>
}

但是没有干净的方法可以从 sscanf 中获取这些信息.如果它返回消耗的字节数，那将很有用.在这种情况下，您可以只使用 strtok，但是能够编写类似于您可以从 stdin 执行的操作会很好:

but there's no clean way to get that information out of sscanf. If it returned the number of bytes consumed, that'd be useful. In cases like this, one can just use strtok, but it'd be nice to be able to write something similar to what you can do from stdin:

int n, sum = 0;
while (1 == scanf(" %d", &n)) {
  sum += n;
  // stdin is transparently advanced by scanf call
}

有没有我忘记的简单解决方案?

Is there a simple solution I'm forgetting?

推荐答案

查找 %n 转换说明符 sscanf() 和家人.它为您提供所需的信息.

Look up the %n conversion specifier for sscanf() and family. It gives you the information you need.

#include <stdio.h>

int main(void)
{
    char line[] = "100 185 400 11 1000";
    char *data = line;
    int offset;
    int n;
    int sum = 0;

    while (sscanf(data, " %d%n", &n, &offset) == 1)
    {
        sum += n;
        data += offset;
        printf("read: %5d; sum = %5d; offset = %5d
", n, sum, offset);
    }

    printf("sum = %d
", sum);
    return 0;
}

将line"更改为data"，因为您无法增加数组的名称.

Changed 'line' to 'data' because you can't increment the name of an array.

这篇关于如何在循环中使用 sscanf?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！