Returning null char array with rewriting Java's String.toUpperCase() [duplicate]

Question

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Convert a String In C++ To Upper Case (31 answers)

Closed 9 years ago.

I am originally a Java programmer and I have a deep love of the syntax, especially regarding the String object. With C++, I have tried to recreate the toUpperCase() method that Java has. The only problem is that it always returns a String object that has an empty/NULL char array.

String String::toUpperCase()
{
    char *a = new char[this->length + 1];
    memset(a, 0, this->capacity + 1);
    memcpy(a, this->characters, this->length);
    for (int i = 0; i < strlen(this->characters); i++)
    {
        toupper(a[i]);
    }
    return *new String(a);
}

Answer 1

You have a few memory problems with your attempt, as well as a logical one. All you need to return a copy of a string with the characters being upper case is:

std::string str = "My Original string";
std::string myCopy(str);
std::locale loc;
std::transform(myCopy.begin(), myCopy.end(), myCopy.begin(), [&](char c)
{
    return std::toupper(c, loc);
});