Question: TypeScript - please help!! How would i modify this square function ( sqr() ) without modifying any other function, so that when i do, for
TypeScript - please help!!
How would i modify this square function (sqr()) without modifying any other function, so that when i do, for ex. 100 / 5^2, i would get the correct answer.
It's the last function at the bottom in bold.... sqr()
/**
* The binary operations supported by the calculator.
*/
export enum Op {
/**
* Addition.
*/
Add,
/**
* Subtraction.
*/
Sub,
/**
* Multiplication.
*/
Mul,
/**
* Division.
*/
Div
}
/**
* A basic four-function calculator. UI logic is handled separately in
* {@link CalculatorUI}.
*/
export class Calculator {
/**
* The contents of the calculator's LCD display.
*/
lcd: string;
/**
* The result of the last operation if `repeat` is `false`, or the second
* argument of the last operation if `repeat` is `true`.
*/
arg: number;
/**
* The last operation that the user entered.
*/
lastOp: Op;
/**
* If `true`, the calculator is in "overwrite mode"; if `false`, the
* calculator is in "append mode". In overwrite mode, the next input replaces
* the current screen contents; in append mode, the next input appends to the
* current screen contents.
*/
overwrite: boolean;
/**
* If `true`, the calculator is in "repeat mode". In repeat mode, when the =
* button is pressed, the screen is updated by re-executing the previous
* operation with the same right-hand argument as last time. For example, if
* the previous operation was 3 + 5 and the calculator is in repeat mode,
* pressing = will update the screen with the number 13.
*/
repeat: boolean;
/**
* In its initial state, the calculator's screen shows `0`, there is no
* previous result or operation, and overwrite mode is enabled.
*/
constructor() {
this.lcd = '0';
this.arg = null;
this.lastOp = null;
this.overwrite = true;
this.repeat = false;
}
/**
* Input a single digit.
* @param x a single digit, 0-9
*/
digit(x: number) {
if (this.overwrite) {
this.lcd = x.toString();
this.overwrite = false;
} else
this.lcd += x;
}
/**
* Input a decimal point.
*/
decimal() {
if (this.overwrite) {
this.lcd = '0.';
this.overwrite = false;
} else if (this.lcd.indexOf('.') === -1) // don't allow more than one '.'
this.lcd += '.';
}
/**
* Negate the current value on the screen.
*/
negate() {
if (this.overwrite) {
this.lcd = '0';
this.overwrite = false;
} else if (this.lcd !== '0') // don't negate '0'
if (this.lcd.charAt(0) === '-')
this.lcd = this.lcd.substring(1)
else
this.lcd = '-' + this.lcd
}
/**
* Input a binary operator. If there is a pending operation whose result has
* not yet been displayed, update the screen to display that result. For
* example, when a user inputs 2 + 4 + 8, the screen is updated to display 6
* on the second + input.
*/
op(o: Op) {
this.overwrite = true;
if (this.arg === null || this.repeat) { // if this is the first argument
this.lastOp = o;
this.arg = parseFloat(this.lcd);
} else { // if this is the second argument
switch (this.lastOp) {
case Op.Add: this.lcd = (this.arg + parseFloat(this.lcd)).toString(); break;
case Op.Sub: this.lcd = (this.arg - parseFloat(this.lcd)).toString(); break;
case Op.Mul: this.lcd = (this.arg * parseFloat(this.lcd)).toString(); break;
case Op.Div: this.lcd = (this.arg / parseFloat(this.lcd)).toString(); break;
}
this.lastOp = o;
this.arg = parseFloat(this.lcd);
}
this.repeat = false;
}
/**
* If the calculator is not in repeat mode, compute the result of the pending
* expression if there is one. If the calculator is in repeat mode,
* re-execute the previous operation.
*
* @see {@link repeat}
*/
equals() {
// If `repeat` is disabled, this press of = will enable it. In that case,
// the value currently on screen is the second argument, the one that's used
// when repeating the operation.
let oldLcd = parseFloat(this.lcd);
// If `repeat` is disabled, then `this.arg` is the first argument to the
// operation; if `repeat` is enabled, then it's the second argument.
// This doesn't matter in the + and * cases because the result is the same
// either way.
switch (this.lastOp) {
case Op.Add: this.lcd = (this.arg + parseFloat(this.lcd)).toString(); break;
case Op.Sub:
if (this.repeat)
this.lcd = (parseFloat(this.lcd) - this.arg).toString();
else
this.lcd = (this.arg - parseFloat(this.lcd)).toString();
break;
case Op.Mul: this.lcd = (this.arg * parseFloat(this.lcd)).toString(); break;
case Op.Div:
if (this.repeat)
this.lcd = (parseFloat(this.lcd) / this.arg).toString();
else
this.lcd = (this.arg / parseFloat(this.lcd)).toString();
break;
}
// If `repeat` is disabled, we need to save the previous value of the screen
// to use it as the second argument when repeating the operation.
if (!this.repeat)
this.arg = oldLcd;
this.repeat = true;
this.overwrite = true;
}
/**
* Clear the screen, resetting it to 0. If in overwrite mode, reset the
* entire calculator to its initial state.
*/
clear() {
if (this.overwrite) {
this.arg = null;
this.lastOp = null;
this.repeat = false;
}
this.lcd = '0';
this.overwrite = true;
}
sqr() {
//let oldLcd = parseFloat(this.lcd);
if (this.overwrite) {
this.lcd = '0';
this.overwrite = false;
} else if (this.lcd !== '0'){
this.arg = parseFloat(this.lcd);
this.lcd = (this.arg * parseFloat(this.lcd)).toString();
}
//if (!this.repeat)
//this.arg = oldLcd;
this.repeat = true;
}
}
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