如何重用stringstream [英] how to reuse stringstream
问题描述
这些线程不会回答我:
std :: ifstream file(szFIleName_p );
if(!file)返回false;
//创建一个字符串流来解析
std :: stringstream szBuffer;
std :: string szLine; //当前行
std :: string szKeyWord; //第一个字在行中标识它包含的数据
while(!file.eof()){
//逐行阅读
std :: getline(file,szLine);
//忽略空行
if(szLine ==)continue;
szBuffer.str();
szBuffer.str(szLine);
szBuffer>> szKeyWord;
szKeyword
将始终包含第一个单词,
新的代码回答:
...
szBuffer.str(szLine);
szBuffer.clear();
szBuffer>> szKeyWord;
...
好的,这就是我的最终版本:
std :: string szLine; //当前行
std :: string szKeyWord; //第一个字在行中标识它包含的数据
//逐行阅读
while(std :: getline(file,szLine)){
//忽略空行
if(szLine ==)continue;
//创建一个字符串流来解析
$ b $ std :: istringstream szBuffer(szLine);
szBuffer>> szKeyWord;
()调用 str()
之后的流。再看看这个答案,它也解释为什么你应该重置使用 str(std :: string())
。在你的情况下,你也可以使用 str(szLine)
来重置内容。 调用 clear()
,流标志(如 eof
)不会被重置,导致令人惊讶的行为。 )
These threads do NOT answer me:
How do you clear a stringstream variable?
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
will always contain the first word, szBuffer
is not being reset, can't find a clear example anywhere on how to use stringstream.
New code after answer:
...
szBuffer.str(szLine);
szBuffer.clear();
szBuffer>>szKeyWord;
...
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;
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)
.
If you don't call clear()
, the flags of the stream (like eof
) wont be reset, resulting in surprising behaviour ;)
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