如何仅用fstream读取包含char、short、float类型数值的CSV文件？

Alright, let's break this down for you. You want to parse a CSV with fixed-order char, short, float values (comma-separated, multi-line) using only the <fstream> header—no stringstream, temp char arrays, or external libraries. Totally doable, here's a straightforward approach:

First, let's define a simple struct to hold each row's data (this keeps things organized instead of juggling separate arrays):

#include <fstream>
#include <vector>

// Match this struct to your fixed column order!
// Example order: char → float → float → short (matches your sample input)
struct CSVRow {
    char id;
    float val1;
    float val2;
    short count;
};

int main() {
    // Open the CSV file
    std::ifstream csv_file("your_data.csv");
    if (!csv_file.is_open()) {
        // Handle file open failure (e.g., print an error message)
        return 1;
    }

    std::vector<CSVRow> dataset; // Store all rows here (use a raw array if you prefer)
    CSVRow current_row;
    char comma; // Dummy variable to consume the commas between values

    // The magic loop: read values and skip commas automatically
    while (csv_file >> current_row.id >> comma 
                    >> current_row.val1 >> comma 
                    >> current_row.val2 >> comma 
                    >> current_row.count) {
        dataset.push_back(current_row);
    }

    // Optional: Verify the data was read correctly
    for (const auto& row : dataset) {
        // Cast char to int to print its numeric value instead of the ASCII character
        std::cout << static_cast<int>(row.id) << ", " 
                  << row.val1 << ", " 
                  << row.val2 << ", " 
                  << row.count << "\n";
    }

    csv_file.close();
    return 0;
}

How This Works (No Tricky Stuff!) #

• No stringstream required: We use std::ifstream's built-in extraction operator (>>), which automatically skips whitespace (including newlines between rows) so we don't have to handle line breaks manually.
• Comma handling: The dummy char comma variable reads and discards the commas separating values. This keeps the extraction sequence perfectly aligned with your CSV structure.
• Flexible storage: std::vector<CSVRow> lets you handle any number of rows without pre-defining an array size. If you must use a raw array, you can first count the rows (loop through the file with getline to count newlines) then allocate the array accordingly.

Key Notes #

• Double-check that your CSV follows the fixed column order exactly—missing values or extra commas will cause the read loop to terminate early.
• If your column type order is different (e.g., short first, then char, then float), just reorder the members in CSVRow and adjust the extraction order in the while loop.
• Whitespace around commas (like 1 , 2.3) is totally fine—the >> operator ignores leading whitespace automatically.

内容的提问来源于stack exchange，提问作者a concerned citizen