知道文本文件中的列数，以空格或制表符分隔 [英] know the number of columns from text file, separated by space or tab

问题描述

我需要知道带有浮点数的文本文件中的列数.

I need to know the number of columns from a text file with floats.

我这样做是为了知道行数:

I've made like this to know the number of lines:

inFile.open(pathV); 

// checks if file opened
if(inFile.fail()) {
    cout << "error loading .txt file for reading" << endl; 
    return;
}
// Count the number of lines
int NUMlines = 0;
while(inFile.peek() != EOF){
    getline(inFile, dummyLine);
    NUMlines++;
}
inFile.close();
cout << NUMlines-3 << endl; // The file has 3 lines at the beginning that I don't read

.txt的一行:

189.53  58.867  74.254  72.931  80.354

值的数量可能因文件而异，但不能在同一文件上.

The number of values can vary from file to file but not on the same file.

每个值在."之后都有可变的小数位数. (点)

Each value have a variable number of decimal places after the "." (dot)

这些值可以用空格或TAB分隔.

The values can be separated by a space or a TAB.

谢谢

推荐答案

给出您已阅读的名为line的行，此行有效:

Given a line you have read, called line this works:

std::string line("189.53  58.867  74.254  72.931  80.354");
std::istringstream iss(line);
int columns = 0;
do
{
    std::string sub;
    iss >> sub;
    if (sub.length())
        ++columns;
}
while(iss);

我不喜欢这样先读取整行，然后重新解析它，但是行得通.

I don't like that this reads the whole line, and then reparses it, but it works.

还有多种其他分割字符串的方法，例如boost的<boost/algorithm/string.hpp>参见上一篇文章此处

There are various other ways of splitting strings e.g. boost's <boost/algorithm/string.hpp> See previous post here

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