Javaの抽象クラスのコンストラクタとオーバーライドの練習

2021.08.09

Javaの抽象クラスのコンストラクタとオーバーライドの練習

import java.util.*;

public class Main {

  public static void main(String[] args) throws Exception {
    Animal a = new Cat(3);
    a.cry();
    System.out.println(a);
  }
}

abstract class Animal {

  protected int age;

  public Animal(int age) {
    this.age = age;
  }

  public abstract void cry();
}

class Cat extends Animal {

  public Cat(int age) {
    super(age);
  }

  @Override
  public void cry() {
    System.out.println("ニャー(" + this.age + ")");
  }

  @Override
  public String toString() {
    return "猫(" + this.age + ")";
  }
}

import java.util.*;

public class Main {

public static void main(String[] args) throws Exception {

Animal a = new Cat(3);

a.cry();

System.out.println(a);

}

abstract class Animal {

protected int age;

public Animal(int age) {

this.age = age;

}

public abstract void cry();

}

class Cat extends Animal {

public Cat(int age) {

super(age);

}

@Override

public void cry() {

System.out.println("ニャー(" + this.age + ")");

}

@Override

public String toString() {

return "猫(" + this.age + ")";

}

2021.08.05

php7.4のアロー関数の練習

<?php

$c = 10;
$add = fn ($x) => $x + $c;
$p = fn ($a) => print($a . "\n");
$runner = fn ($func, $arg) => $func($arg);
$runner($p, $runner($add, 5));

<?php

$c = 10;

$add = fn ($x) => $x + $c;

$p = fn ($a) => print($a . "\n");

$runner = fn ($func, $arg) => $func($arg);

$runner($p, $runner($add, 5));

15

2021.08.04

関数ポインタ決定版

#include <stdio.h>

void hello()
{
  printf("こんにちは\n");
}

int sum(int a, int b)
{
  return a + b;
}

void higher_order_hello(void (*f)())
{
  f();
}

int higher_order_sum(int (*f)(), int a, int b)
{
  return f(a, b);
}

int main()
{
  void (*hello_ptr)() = hello;
  int (*sum_ptr)() = sum;

  higher_order_hello(hello_ptr);
  int ret = higher_order_sum(sum_ptr, 2, 3);

  printf("%d\n", ret);
  return 0;
}

#include <stdio.h>

void hello()

{

printf("こんにちは\n");

}

int sum(int a, int b)

{

return a + b;

}

void higher_order_hello(void (*f)())

{

f();

}

int higher_order_sum(int (*f)(), int a, int b)

{

return f(a, b);

}

int main()

{

void (*hello_ptr)() = hello;

int (*sum_ptr)() = sum;

higher_order_hello(hello_ptr);

int ret = higher_order_sum(sum_ptr, 2, 3);

printf("%d\n", ret);

return 0;

}

こんにちは
5

こんにちは

2021年 8月の投稿一覧