dave88

#include <iostream>

void TrimStringLeft(std::string& str)
{
   int i = 0;
   int e = (int)str.size();
   for (i; i!=e; ++i)
   {
      if (!isspace(str[i]))
         break;
   }
   if (i!=0 && i<e)
      str = str.substr(i);
}

std::string TrimStringLeft2(const std::string& str)
{
    size_t cut(0);
    for (std::string::const_iterator it = str.begin(); it != str.end() && isspace(*it); ++cut, ++it);
    return str.substr(cut);
}

int main(int argc, char *argv[])
{
    const std::string s(argc > 1 ? argv[1] : "   abc");
    std::string s1(s), s2(s);
    TrimStringLeft(s1);
    s2 = TrimStringLeft2(s2);
    std::cout << s1 << std::endl;
    std::cout << s2 << std::endl;
    return 0;
}