如何重用字符串流 [英] how to reuse stringstream

问题描述

这些线程不回答我:

重置字符串流

如何清除字符串流变量?

std::ifstream file( szFIleName_p );
if( !file ) return false;

// create a string stream for parsing

std::stringstream szBuffer;

std::string szLine;     // current line
std::string szKeyWord;  // first word on the line identifying what data it contains

while( !file.eof()){

    // read line by line

    std::getline(file, szLine);

    // ignore empty lines

    if(szLine == "") continue;

    szBuffer.str("");
    szBuffer.str(szLine);
    szBuffer>>szKeyWord;

szKeyword 将始终包含第一个单词，szBuffer 不会被重置.我在任何地方都找不到关于如何使用 stringstream 的明确示例.

szKeyword will always contain the first word, szBuffer is not being reset. I can't find a clear example anywhere on how to use stringstream.

回答后的新代码:

...
szBuffer.str(szLine);
szBuffer.clear();
szBuffer>>szKeyWord;
...

好的，这是我的最终版本:

Ok, thats my final version:

std::string szLine;     // current line
std::string szKeyWord;  // first word on the line identifying what data it contains

// read line by line

while( std::getline(file, szLine) ){

    // ignore empty lines

    if(szLine == "") continue;

    // create a string stream for parsing

    std::istringstream szBuffer(szLine);
    szBuffer>>szKeyWord;

推荐答案

您在调用 str("") 后没有 clear() 流.再看看这个答案，它还解释了为什么你应该使用 str(std::string()) 重置.在您的情况下，您还可以仅使用 str(szLine) 重置内容.

You didn't clear() the stream after calling str(""). Take another look at this answer, it also explains why you should reset using str(std::string()). And in your case, you could also reset the contents using only str(szLine).

如果你不调用clear()，流的标志(如eof)不会被重置，导致令人惊讶的行为;)

If you don't call clear(), the flags of the stream (like eof) wont be reset, resulting in surprising behaviour ;)

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