問題描述

我正在用 C++ 讀取 CSV 文件，行格式如下:

I'm reading a CSV file in C++ and the row format is as such:

小學，中學，第三"，主要"，，中學"，18, 4, 0, 0, 0

"Primary, Secondary, Third", "Primary", , "Secondary", 18, 4, 0, 0, 0

(注意空值)

當我這樣做時:

while (std::getline(ss, csvElement, ',')) {
   csvColumn.push_back(csvElement);
}

這會將第一個字符串分成不正確的部分.

This splits up the first string into pieces which isn't correct.

如何在迭代時保留字符串?我嘗試將上述方法結合起來，同時還抓取了由雙引號分隔的行，但我得到了瘋狂的結果.

How do I preserve the string when iterating? I tried to do a combination of the above and while also grabbing the lines separated by double quote but I got wild results.

推薦答案

您需要根據是否在引號之間來解釋逗號.這對于 getline() 來說太復雜了.

You need to interpret the comma depending on whether you're betwwen the quote or not. This is too complexfor getline().

解決方案是使用 getline() 讀取整行，并通過逐個字符遍歷字符串來解析該行，并維護一個指示符是否在雙引號之間.

The solution would be to read the full line with getline(), and parse the line by iterating through the string character by character, and maintaing an indicator whether you're between double quotes or not.

這是第一個原始"示例(未刪除字段中的雙引號且不解釋轉義字符):

Here is a first "raw" example (double quotes are not removed in the fields and escape characters are not interpreted):

string line; 
while (std::getline(cin, line)) {        // read full line
    const char *mystart=line.c_str();    // prepare to parse the line - start is position of begin of field
    bool instring{false};                
    for (const char* p=mystart; *p; p++) {  // iterate through the string
        if (*p=='"')                        // toggle flag if we're btw double quote
            instring = !instring;     
        else if (*p==',' && !instring) {    // if comma OUTSIDE double quote
            csvColumn.push_back(string(mystart,p-mystart));  // keep the field
            mystart=p+1;                    // and start parsing next one
        }
    }
csvColumn.push_back(string(mystart));   // last field delimited by end of line instead of comma
}

在線演示

這篇關于帶有逗號和雙引號內的字符串的 C++ CSV 行的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！