How can I alphabetize strings from an array in c++?

问题

I have to write a program that sorts 10 people by height, then by last name. I've got the height down, but i can't get the last name sort to work. I'm trying to use strcmp for it. Any time I try to run it though, it flags an error at the strcmp saying, "[Error] cannot convert 'std::string {aka std::basic_string}' to 'const char*' for argument '1' to 'int strcmp(const char*, const char*)'" I'm using strcmp because this is for a school assignment and I am limited by my knowledge of c++ and what my professor allows us to use

int main()
{
    const int SIZE = 10;
    int count = 0;
    bool flag = true;
    string fileName;
    ifstream inputFile;
    string firstName[SIZE];
    string lastName[SIZE];
    int height[SIZE];

    cin >> fileName;
    inputFile.open(fileName.c_str());

    while(count < 10)
    {
        inputFile >> firstName[count];
        inputFile >> lastName[count];
        inputFile >> height[count];
        count++;
    }
    //Sort based on height
    for(int max = SIZE - 1; max > 0 && flag; max--)
    {
        flag = false;

        for(int line = 0; line < max; line++)
        {
            if(height[line] > height[line + 1])
            {
                swap(height[line], height[line + 1]);
                swap(firstName[line], firstName[line + 1]);
                swap(lastName[line], lastName[line + 1]);
                flag = true;
            }
        }
    }
    //Sort based on last name if heights are equal
    for(int max = SIZE - 1; max > 0 && flag; max--)
    {
        flag = false;

        for(int line = 0; line < max; line++)
        {
            if(height[line] == height[line + 1])
            {
                if(strcmp(lastName[line], lastName[line + 1]) > 0)
                {
                    swap(height[line], height[line + 1]);
                    swap(firstName[line], firstName[line + 1]);
                    swap(lastName[line], lastName[line + 1]);
                    flag = true;
                }
            }
        }
    }

回答1:

If you insist on using the old strcmp function, then you should pass lastName[line].c_str() and lastName[line+1].c_str()as its argument(s). However, you'd be better off using the std::string::compare() function provided by the STL:

if (lastName[line].compare(lastName[line + 1]) > 0)

This does much the same thing.

Or even simpler (as Fred Larson has suggested):

if (lastName[line] > lastName[line+1])

来源：https://stackoverflow.com/questions/59036335/how-can-i-alphabetize-strings-from-an-array-in-c