Calculator

Build a simple arithmetic calculator.

Meta

Lab	Source File	Description	Due Date
3	calc.cpp	Simple arithmetic calculator w/error handling	2/16/2023 - 11:59pm

Introduction

I'm not going to go over much here, since the program is really simple honestly. I'll just cover a couple of the main points of this lab.

Program Flow

Your program should do a few things:

1. Prompt user for the left operand.
2. Prompt user for operator.
3. Prompt user for the right operand. Operate and output the result.

Note that the operands are integers, while the operator is a single character. You should use a switch statement to determine which operation to perform.

note

The only exception to this flow is the absolute value operation. This operation only requires one operand, so you should prompt the user for only one operand.

Requirements

• You cannot re-use code. Don't repeat something you've already done.
• You must use a switch statement.
• You must handle erroneous input. If the user enters an invalid operator, you should output the appropriate error message and exit the program.

Error Handling

Operands

You should handle erroneous input. If the user enters an invalid operator, you should output an error message and exit the program. You can check for invalid input using the cin.fail() function. This function returns true if the last input operation failed. You can use this function to check if the user entered an invalid operator.

int my_int;
cin >> my_int;

// a failure occurs if the user entered something other than an integer
if (cin.fail()) {
    cout << "Invalid left operand" << endl;
    return 1;
}

Alternatively, you can check the result of the cin operation directly.

int my_int;

// returns false if the user entered something that doesn't match the type of x
if (!(cin >> my_int)) {
    cout << "Invalid left operand" << endl;
    return 1;
}

Operators

In the case that an invalid operator is entered, you should run the program like normal. If the operator does not exist in your switch statement, then it will use the default case. In the default case, you should output an error message and exit the program.

Hints

• cin.get() - This function is used to get a single character from the user. It's not necessary as it's interchangeable with cin >> my_char, but you can use it.

• cin.ignore() - This function is used to ignore the rest of the line. This is useful when you want to get a single character from the user, but there is still data left in the input buffer. So if the user enters Agfjdkl for their operator, and you use cin.get() to get the first character, the rest of the line will still be in the "input buffer", which is where input that hasn't been read is stored to be read later. So the next time you try to get an integer from the user, it will get gfjdkl instead of the integer they entered. So you can use cin.ignore() to ignore the rest of the line. This way, the next time you try to get an integer from the user, it will get the integer they entered.

cin.ignore() takes 2 arguments. 1. The number of characters to ignore, 2. The character to stop ignoring at. Whichever comes first. For ignoring, typically we want to ignore as many characters as physically possible or until we hit a \n character. Luckily, C++ has a constant for the largest number: numeric_limits<streamsize>::max().

// will ignore anything in the input buffer until it hits a newline character
cin.ignore(numeric_limits<streamsize>::max(), '\n');

Include <limits>

You must include #include<limits> to use numeric_limits.