检查是否所有值均已成功从std :: istream读取 [英] Check if all values were successfully read from std::istream

问题描述

假设我的文件具有

100 text

如果我尝试使用ifstream读取2个数字，则会失败，因为text不是数字.通过使用fscanf，我将通过检查其返回码来了解它是否失败:

If I try reading 2 numbers using ifstream, it would fail because text is not a number. Using fscanf I'll know it failed by checking its return code:

if (2 != fscanf(f, "%d %d", &a, &b))
    printf("failed");

但是当使用iostream代替stdio时，我怎么知道它失败了?

But when using iostream instead of stdio, how do I know it failed?

推荐答案

实际上(如果不是更多的话)很简单:

Its actually as (if not more) simple:

ifstream ifs(filename);
int a, b;
if (!(ifs >> a >> b))
   cerr << "failed";

顺便说一下，习惯了这种格式. (非常方便)(对于通过循环继续 positive 持续进展更是如此)

Get used to that format, by the way. as it comes in very handy (even more-so for continuing positive progression through loops).

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