如何从C ++中的字符串中删除前导小写字母，下划线？

Question

here i have a string but i need to remove the lower case letter only ie, mi.

primitive code is:

bool check(char c) { return !(std::isdigit(c) ||std::isalpha(c)); }

int main() {

    std::string  str = "m_ivecCadCurveEdges_Pattern";

    str.erase(std::remove_if(str.begin(), str.end(), check),str.end());

    for (std::string::size_type i=0; i<str.length(); ++i)
    {
       //if (!std::islower(str.at(i) && str.at(i) != '_')
       if (!std::islower(str.at(i)))
        {
            str.erase(0, i);
            break;
        }
    }

    if (std::isdigit(str.at(0)))
        str= "N" + str;

    std::cout<<str;
}

I want to break the loop once it reach B in the string.

Answer 1

Looking at the title I suggest you use a combination of remove_if and islower . However the question body implies that you may need to remove only the longest prefix of lower case characters. If that is the case you will need a combination of std::string#erase and find_if for isupper .

Answer 2

erase-remove is good if you wanted the whole string processed, but you ask to have only the leading lower-case character changed. For that, just change your "if" code:

if (!std::islower(str.at(i))
{
    str.erase(0, i);
    break;
}

Your cout should be after the for loop.