通过对程序的编写，可以不同位数实现对加减乘除的计算 ，以及对错误答案给出提示。以满足一些大人给小孩出题的困惑 ，此程序可以自己出题，自己检测答案。随时随地想做就做。
需求：
1.实现计算器的基本功能。 2.可以练习加减乘除的计算，以提高自己算题的速度 和探索新的解题方式。
代码的实现
public class day01 { public static void main(String[] args) { System.out.println(); System.out.println("|----------欢迎使用计算器！------------|"); System.out.println("|--------1.加法运算 2.减法运算------|"); System.out.println("|--------3.乘法运算 4.除法运算------|"); System.out.println("|--------0.退出 -----|"); System.out.println("|--------------------------------------|"); System.out.println("|请选择0-4："); Scanner input = new Scanner(System.in); int num = input.nextInt(); int a = 0; switch (num) { case 1: System.out.println("请输入计算范围："); int num1 = new Scanner(System.in).nextInt(); int num2 = new Scanner(System.in).nextInt(); a: while (true) { int number1 = new Random().nextInt(num2); int number2 = new Random().nextInt(num2); if (number1 >= num1 & number2 >= num1) { System.out.print(number1 + "+" + number2 + "="); int num3 = new Scanner(System.in).nextInt(); if (number1 + number2 == num3) { System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } else { for (int i = 0; i < 2; i++) { System.out.print(number1 + "+" + number2 + "="); int num5 = new Scanner(System.in).nextInt(); if (number1 + number2 == num5) { System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } } System.out.println(number1 + "+" + number2 + "=" + (number1 + number2)); System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } } } break; case 2: System.out.println("请输入计算范围："); int num11 = new Scanner(System.in).nextInt(); int num12 = new Scanner(System.in).nextInt(); a: while (true) { int number1 = new Random().nextInt(num12); int number2 = new Random().nextInt(num12); if (number1 >= num11 & number2 >= num11) { System.out.print(number1 + "-" + number2 + "="); int num3 = new Scanner(System.in).nextInt(); if (number1 - number2 == num3) { System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } else { for (int i = 0; i < 2; i++) { System.out.print(number1 + "-" + number2 + "="); int num5 = new Scanner(System.in).nextInt(); if (number1 - number2 == num5) { System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } } System.out.println(number1 + "-" + number2 + "=" + (number1 - number2)); System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } } } break; case 3: System.out.println("请输入计算范围："); int num21 = new Scanner(System.in).nextInt(); int num22 = new Scanner(System.in).nextInt(); a: while (true) { int number1 = new Random().nextInt(num22); int number2 = new Random().nextInt(num22); if (number1 >= num21 & number2 >= num21) { System.out.print(number1 + "×" + number2 + "="); int num3 = new Scanner(System.in).nextInt(); if (number1 * number2 == num3) { System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } else { for (int i = 0; i < 2; i++) { System.out.print(number1 + "×" + number2 + "="); int num5 = new Scanner(System.in).nextInt(); if (number1 * number2 == num5) { System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } } System.out.println(number1 + "×" + number2 + "=" + (number1 * number2)); System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } } } break; case 4: System.out.println("请输入计算范围："); int num31 = new Scanner(System.in).nextInt(); int num32 = new Scanner(System.in).nextInt(); a: while (true) { int number1 = new Random().nextInt(num32); int number2 = new Random().nextInt(num32); if (number1 >= num31 & number2 >= num31) { System.out.print(number1 + "÷" + number2 + "="); int num3 = new Scanner(System.in).nextInt(); if (number1 / number2 == num3) { System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } else { for (int i = 0; i < 2; i++) { System.out.print(number1 + "÷" + number2 + "="); int num5 = new Scanner(System.in).nextInt(); if (number1 / number2 == num5) { System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } } System.out.println(number1 + "÷" + number2 + "=" + (number1 / number2)); System.out.println("是否继续：(y/n):"); String num4 = new Scanner(System.in).next(); if (num4.equals("y")) { continue a; } else { System.out.println("已退出！"); break; } } } } break; case 0: System.out.println("已退出！"); break; } } }好了，我亲爱的读者朋友，以上就是本文的全部内容了！！！
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通过坚持不懈地学习，持续不断地输出，你的编程基本功算得上是突飞猛进。
为了帮助更多的程序员，专注于分享有趣的 Java 技术编程和有益的程序人生。一开始，阅读量寥寥无几，关注人数更是少得可怜。但随自己的不断努力，阅读量和关注人都在猛烈攀升。
绝对不容错过，期待与你的不期而遇。
