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Marmis

A fast way of filling std::map

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I have a file which has the following kind of structure: fooo 7214 bar 12 foofoo 1234 ... What would be a quick way of filling up a std::map<std::string, unsigned> container with these lines found from the file? I think my previous approaches have been a bit clumsy and I'm fairly confident that this could be achieved in a more convenient way. Any help is appreciated, thanks in advance! [Edited by - Marmis on January 2, 2007 10:29:05 AM]

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What's wrong with:

string key;
unsigned int val;
while (fileIn >> key) { fileIn >> val; themap[key] = val; }

Cheers,
--Brian

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#include <iostream>
#include <sstream>
#include <string>
#include <map>

template<class Key, class Value, class Pred, class Alloc>
int load_map( std::istream& is, std::map<Key, Value, Pred, Alloc>& m )
{
std::string line;
std::istringstream iss;
std::pair<Key, Value> data;
int errors = 0;

while(!is.eof())
{
// Remove leading whitespace
is >> std::ws;

// Get the rest of the line
getline(is, line);

// Treat # as marking the beginning of a comment.
int comment = line.find('#');
if (comment != std::string::npos)
line.erase( comment );

// Nothing to do if the line is empty.
if (line.empty())
continue;

// Read the map fields.
iss.clear();
iss.str(line);
iss >> data.first >> data.second;

// If successful, put the data in the map.
if(!iss.fail())
m.insert(data);
else
++errors;
}

return errors;
}

std::string test =
"abc 123\n" // Reads ok
" def 456\n" // Reads ok, leading whitespace is removed
"ghi\n" // Missing field, skipped
"\n" // Empty, skipped
"klm 789 # howdy ?\n" // Reads ok
"nop #999\n" // Field commented out, skipped
"#qrs 343\n" // Line commented out, skipped
"tuv wxy" // Second field is garbage, skipped
;

int main()
{
std::istringstream iss(test);
std::map<std::string, int> m;
int errors = load_map(iss, m);

std::map<std::string, int>::iterator itor;
for(itor = m.begin(); itor != m.end(); ++itor)
std::cout << itor->first << ' ' << itor->second << std::endl;

std::cout << errors << " read errors." << std::endl;
}



[Edited by - Fruny on November 6, 2006 1:52:56 PM]

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