小编Mon*_*nil的帖子

我正在尝试djangoproject.com网站上的Django教程,但当我到达我做第一个"makemigrations民意调查"的部分时,我不断收到此错误:

ImportError:没有名为apps的模块

Traceback (most recent call last):
  File "manage.py", line 22, in 
    execute_from_command_line(sys.argv)
  File "/Library/Python/2.7/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
    utility.execute()
  File "/Library/Python/2.7/site-packages/django/core/management/__init__.py", line 312, in execute
    django.setup()
  File "/Library/Python/2.7/site-packages/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/Library/Python/2.7/site-packages/django/apps/registry.py", line 85, in populate
    app_config = AppConfig.create(entry)
  File "/Library/Python/2.7/site-packages/django/apps/config.py", line 112, in create
    mod = import_module(mod_path)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)

我该如何解决这个错误？

我试图使用一个Abstract类Employee,它有两个子类,HourlyEmployee和AnnualEmployee.在Employee课堂上我有一个抽象的方法:

员工类:

public abstract class Employee{
    public abstract double computePay();
}

每小时雇员班级:

public class HourlyEmployee extends Employee{
    public double computePay(double rate, double hours){
        double monthlySalary;
        monthlySalary = ((rate * hours) * 52) / 12;
        return monthlySalary;
    }
}

年度员工类:

public class AnnualEmployee extends Employee{
    public double computePay(double salary){
        double monthlySalary;
        monthlySalary = salary / 12;
        return monthlySalary;
    }
}

错误说没有HourlyEmployee,也不AnnualEmployee是抽象的,因此不能重写抽象方法computePay()在Employee.

我不明白为什么我不能为这种方法提供两个不同的参数.由于我无法做到这一点,我该如何解决这个问题呢？

我有一个stringin main,我想将该字符串的地址传递给一个将编辑该字符串内容的函数.我不想使用malloc.

我的代码目前看起来像这样:

int main(){
        char* str = "Hello";
        char* para1[] = {"Tea", "Coffee"};

        printf("str: %s\n para1: %s\n", str, para1[0]);

        my_func(str, &para1);

        printf("str: %s\n para1: %s\n", str, para1[0]);

        return 1;
}

int my_func(char* str, char** para1){
        printf("str: %s\n", str);
        str[0] = 'W';
        para1[0] = "Popcorn";

        return 1;
}

我不明白如何将字符串的第一个字母更改H为W

你能解释一下我做错了什么吗？