从文件C ++读取 [英] Read from a file C++

问题描述

您好，我想从VTK文件中读取数据到我的C ++程序。
这里是我的文件通常看起来。

POINTS 2双人

1 2

3 4

POINT_DATA 2

SCALARS压力双重

LOOKUP_TABLE预设

5

6

SCALARS密度双重

LOOKUP_TABLE预设

7

8 b
$ b

我想将数据数据以粗体突出显示在我的C ++程序中，但我不知道如何忽略数据之间的文本行。

更准确地说：我有数组 xp [2]，yp [2]，pressure [2]，density [2] code>

我要放置

  0] = 1 yp [0] = 2 
 
 xp [1] = 3 yp [1] = 4 
 
 pressure [0] = 5 pressure [1] = 6 
 
 density [0] = 7 density [1] = 8 
  

不知道如何做到这一点，因为有数字之间的文本，我必须放入我的数组。

解决方案

您可以使用 ignore 函数不是数字。使用 cin>> x 从输入文件读取值x。如果失败，则在输入流中设置 failbit ，您必须清除。然后，忽略整行。

  std :: vector< int>数据; 
 while（！cin.eof（））
 {
 int x; 
 if（cin>> x）{
 data.push_back（x）; 
 if（data.size（）== 8）
 {
 //使用8个数字做任何你想要的操作
 data.clear（）; 
} 
} else {
 cin.clear（）; 
 cin.ignore（1000，'\\\
'）; //假设最大行长小于1000 
} 
} 
  

代码假设从 cin 读取，重定向到另一个输入文件）

Hi I want to read data from a VTK file into my C++ program. Here is how my files will typically look.

POINTS 2 double

1 2

3 4

POINT_DATA 2

SCALARS pressure double

LOOKUP_TABLE default

5

6

SCALARS density double

LOOKUP_TABLE default

7

8

I want to put the numerical data highlighted in bold into my C++ program but I dont know how to ignore the text lines in between the data.

To be more precise: I have arrays xp[2], yp[2], pressure[2] , density[2]

I want to put

              xp[0]=1 yp[0]=2 

              xp[1]=3  yp[1]=4

              pressure[0]=5 pressure[1]=6

              density[0]=7  density[1]=8

I dont know how to do this since there is text between the numbers that I have to put into my arrays.

解决方案

You can use the ignore function to throw away lines of text that are not numbers. Use cin >> x to read a value x from the input file. If that fails, the failbit is set in the input stream, which you must clear. Then, ignore the whole line.

std::vector<int> data;
while (!cin.eof())
{
    int x;
    if (cin >> x) {
        data.push_back(x);
        if (data.size() == 8)
        {
            // do whatever you need with the 8 numbers
            data.clear();
        }
    } else {
        cin.clear();
        cin.ignore(1000, '\n'); // assuming maximum line length less than 1000
    }
}

(This code assumes reading from cin, which is redirected to another input file)

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