C ++读取多个列的文件 [英] C++ Read File with multiple column

问题描述

我想读取一个包含多个列，不同变量类型的文件。列数不确定，但在2或4之间。例如，我有一个文件：

I'd like to read a file with multiple columns, different variable types. The number of columns is uncertain, but between 2 or four. So for instance, I have a file with :

• string int


• string int string double


• string int string


• string int string double

• string int
• string int string double
• string int string
• string int string double

谢谢！

我编辑，将列数更正为2或5，而不是4五是原来写的。

I edited to correct the number of columns to between 2 or 5, not 4 or five as originally written.

推荐答案

您可以先阅读 std :: getline

You can first read the line with std::getline

std::ifstream f("file.txt");
std::string line;
while (std::getline(f, line)) {
...
}

，然后使用 stringstream

and then parse this line with a stringstream

std::string col1, col3;
int col2;
double col4;
std::istringstream ss(line);
ss >> col1 >> col2;
if (ss >> col3) {
    // process column 3
    if (ss >> col4) {
        // process column 4
    }
}

如果列可能包含不同类型，则必须首先读入字符串然后尝试确定正确的类型。

If the columns might contain different types, you must first read into a string and then try to determine the proper type.

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