在 If/Switch 语句中使用用户输入的字符 [英] Using user-inputted characters in If/Switch statements

问题描述

我正在参加我的第一门 Java 课程，并且很难完成这项作业.

I am taking my first Java class, and am having a hard time finishing this assignment.

任务本身非常简单.我所要做的就是提示用户输入一个整数、一个字符，然后是另一个整数.

The assignment itself is quite simple. All I have to do is prompt the user to input an integer, a character, then another integer.

如果输入的字符是+，两个整数要相加.如果输入的字符是-，则两个整数相减.等等...

If the character inputted is +, the two integers should be added together. If the character inputted is -, the two integers should be subtracted. Etc...

问题是我不知道如何从用户那里接受一个字符，然后在我的 If/Switch 语句中使用它.

这是我的提示:

// Prompt the user to enter an integer
    System.out.print("Please enter an integer number:");
    int int1  = input.nextInt();

// Prompt the user to enter a character
// Since I could not use characters, I am using integers to represent them.
    System.out.print("Enter 0 for +, 1 for -, 2 for /, 3 for %, and 4 for *");
    int char1 = input.nextInt();

// Prompt the user to enter another integer
    System.out.print("Please enter another integer number:");
    int int2 = input.nextInt();

这是我的 If/Switch 语句:(我知道它们是多余的，但它是作业的一部分)

Here are my If/Switch statements: (I know they are redundant, but it's part of the assignment)

if (char1 == 0) {
    int ans = int1 + int2;
    System.out.println(int1 + " + " + int2 + " = " + ans);
} else if (char1 == 1) {
    int ans = int1 - int2;
    System.out.println(int1 + " - " + int2 + " = " + ans);
} else if (char1 == 2) {
    int ans = int1 / int2;
    System.out.println(int1 + " / " + int2 + " = " + ans);
} else if (char1 == 3) {
    int ans = int1 % int2;
    System.out.println(int1 + " % " + int2 + " = " + ans);
} else if (char1 == 4) {
    int ans = int1 * int2;
    System.out.println(int1 + " * " + int2 + " = " + ans);
} else
    System.out.println("Invalid operator");

int result = 0;
switch (char1) {
    case 0: result = int1 + int2;
            System.out.println(int1 + " + " + int2 + " = " + result); break;
    case 1: result = int1 - int2;
            System.out.println(int1 + " - " + int2 + " = " + result); break;
    case 2: result = int1 / int2;
            System.out.println(int1 + " / " + int2 + " = " + result); break;
    case 3: result = int1 % int2;
            System.out.println(int1 + " % " + int2 + " = " + result); break;
    case 4: result = int1 * int2;
            System.out.println(int1 + " * " + int2 + " = " + result); break;
    default: System.out.println("Invalid operator");
}

其他一切正常.我只是想从使用 0 表示 +、1 表示 - 更改为仅使用 +、-、/、% 和 *.

Everything else works just fine. I'm just trying to change from using 0 for +, 1 for -, to just using +, -, /, %, and *.

推荐答案

您可以从用户处获取运算符为 String 或 Char

you can take the operator from the user as String or Char

像这样:

 Scanner input = new Scanner(System.in);
        // Prompt the user to enter an integer
        System.out.print("Please enter an integer number:");
        int int1 = input.nextInt();

// Prompt the user to enter a character
// Since I could not use characters, I am using integers to represent them.
        System.out.print("Enter +, -,  /,  %, *");
        char char1 = input.next().charAt(0);

// Prompt the user to enter another integer
        System.out.print("Please enter another integer number:");
        int int2 = input.nextInt();

        if (char1=='+') {
            int ans = int1 + int2;
            System.out.println(int1 + " + " + int2 + " = " + ans);
        } else if (char1=='-') {
            int ans = int1 - int2;
            System.out.println(int1 + " - " + int2 + " = " + ans);
        } else if (char1=='/') {
            int ans = int1 / int2;
            System.out.println(int1 + " / " + int2 + " = " + ans);
        } else if (char1=='%') {
            int ans = int1 % int2;
            System.out.println(int1 + " % " + int2 + " = " + ans);
        } else if (char1=='*') {
            int ans = int1 * int2;
            System.out.println(int1 + " * " + int2 + " = " + ans);
        } else {
            System.out.println("Invalid operator");
        }

        int result = 0;

        switch (char1) {
            case '+':
                result = int1 + int2;
                System.out.println(int1 + " + " + int2 + " = " + result);
                break;
            case '-':
                result = int1 - int2;
                System.out.println(int1 + " - " + int2 + " = " + result);
                break;
            case '/':
                result = int1 / int2;
                System.out.println(int1 + " / " + int2 + " = " + result);
                break;
            case '%':
                result = int1 % int2;
                System.out.println(int1 + " % " + int2 + " = " + result);
                break;
            case '*':
                result = int1 * int2;
                System.out.println(int1 + " * " + int2 + " = " + result);
                break;
            default:
                System.out.println("Invalid operator");
        }

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