Examples of istringstream

Some examples of istringstream, which is fun:

Sample 1: 

m_string::cacluation_string(const string & s) {

if (s.empty() || s.length() < 3) {

return "";

}

if ((s[0] != '-') && (s[0] < '0') && (s[0] > '9')) {

return "";

}

string oper1, oper2;

for(int i = 1; i < s.length(); i++) {

if (s[i] == '+' || s[i] == '-') {

oper1 = s.substr(0, i);

oper2 = s.substr(i);

break;

}

}

int iOper1, iOper2;

std::istringstream iss(oper1);

iss >> iOper1;

std::istringstream iss2(oper2);

iss2 >> iOper2;

string sret = "";

std::stringstream out;

out << iOper1 + iOper2;

sret = out.str();

cout<<" --- "<<sret<<endl;

return sret;

}

======Sample 2===========

ifstream file;

file.open("file.txt");

string line;

getline(file,line);

istringstream iss(line);

iss >> id;

getline(file,line);

istringstream iss2(line);

iss2 >> id;

getline(file,line);

iss.clear()

iss.str(line);

iss >> id;

======Sample 3===========

The "str()" and "str( string )" methods should work.

However, on some platforms these may not work so you

may use the ugly reconstruct hack.

#include <sstream>

#include <iostream>

int main()

{

std::istringstream iss( "Hi there" );

std:stringstream oss;

std::string foo;

iss >> foo;

oss << foo;

iss.str( "boo hoo" ); // Set the input to new string

iss >> foo;

oss << foo;

std::cout << oss.str() << "\n";

// Another way is to reconstruct the istringstream

// UGLY but some implementations have bugs and this is the

// only way.

iss.~istringstream();

new ( (void *) &iss ) std::istringstream( "Reconstruct this" );

oss.str( "" ); // reset the output string.

iss >> foo;

oss << foo;

std::cout << oss.str() << "\n";

// Another way is to reconstruct the ostringstream

oss.~ostringstream();

new ( (void *) &oss ) std:stringstream;

iss >> foo;

oss << foo;

std::cout << oss.str() << "\n";

}

Refs: http://www.velocityreviews.com/forums/t278533-std-stringstream-reset.html

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