string 去掉空格

std::string 去空格，或找内容

std::string trim(std::string & str) 
{ 
std::string::size_type pos = str.find_last_not_of(' '); 
if(pos != std::string::npos) 
{ 
str.erase(pos + 1); 
pos = str.find_first_not_of(' '); 
if(pos != std::string::npos) str.erase(0, pos); 
} 
else 
str.erase(str.begin(), str.end()); 
return str; 
} 

std::string ResolveQRCode(const std::string & strCode,std::string strFind)
{
std::string strBack ="";
// std::string strFind = "CodeldData=";
int nstrCount = strCode.length();
int nfindLen = strFind.length();
if(nstrCount<=0 || nfindLen<=0)
return strBack;
int nPos = strCode.find_last_of(strFind);
if(nPos!=-1)
{
if(nPos+1<nstrCount)
strBack = strCode.substr(nPos+1,nstrCount-nPos-1);
}