C Search using lower_bound in the vector and ignore lowercase / uppercase letters-CodePudding

How can I find an element in a vector if I don't care about case. For example, if I have in cmp name = "tOM" addr = "LONDON" and I want it to find an element with values name = "Tom" addr = "London" that I have saved in vector? I enclose the whole program https://onecompiler.com/cpp/3xy2j7dmd .

bool Company::cmpNA2 (const Company &a, const Company &b) 
{
    if ( (strcasecmp(a.getName().c_str(), b.getName().c_str()) != 0) )
        return ( strcasecmp(a.getName().c_str(), b.getName().c_str()) );
    
    return ( strcasecmp(a.getAddr().c_str(), b.getAddr().c_str()));
}

bool CVATRegister::invoice ( const string  &name, const string &addr, unsigned int amount )
{
    Company cmp(name, addr,"-1");

    sort(DCompany.begin(), DCompany.end(), [](const Company & a, const Company & b)
        { 
            if ( (strcasecmp(a.getName().c_str(), b.getName().c_str()) != 0) )
                 return ( strcasecmp(a.getName().c_str(), b.getName().c_str()) );
    
            return ( strcasecmp(a.getAddr().c_str(), b.getAddr().c_str()));
        });

    auto itr = lower_bound(DCompany.begin(), DCompany.end(), cmp, &Company::cmpNA2);

    // cout << itr->getTotalIncome() << itr->getId() << endl; <--- Nothing

CodePudding user response：

The first thing is that std::sort requires you to return true or false. The issue is that strcasecmp returns an int denoting whether the first item comes before, is equal, or after the second item (-1, 0, 1). That's three values, not just true or false.

To simplify your code, you could do something similar to this:

bool CVATRegister::invoice ( const string  &name, const string &addr, unsigned int amount )
{
    std::sort(DCompany.begin(), DCompany.end(), [](const Company & a, const Company & b)
    { 
      return strcasecmp(a.getName().c_str(), b.getName().c_str()) < 0;
    });
}

Since strcasecmp returns -1 if the first item is placed before the second item, then the predicate simply returns true if the result is < 0, and false otherwise.