Looking to round the final answer to 2 decimals C++

Question

I'm trying to round my final answer to 2 decimals so it is Dollars and Cents. I'm new to coding, and can't figure it out. I want to round "w" in the line that says "The amount you need to charge is" Here's my code:

#include <iostream>

using namespace std;

int main()
{
    string Choice;


    float x, w;

    cout << "Please enter the amount needed." << endl;
    cin >> x;


    w = x/(1-0.0275);   

    cout << "The amount you need to charge is $"<< w << "." << endl;

    return (0);

}

You can't express most decimals exactly with floats. Use integers and calculate using pennies. — Peter Wood, Mar 03 '13 at 18:28

Tim · Accepted Answer · 2013-03-03T18:35:11.453

4

According to the example here http://www.cplusplus.com/forum/beginner/3600/ You could use

cout << setprecision(2) << fixed << w << endl;

(fixed is optional)

You will have to #include <iomanip>

As pointed out by Synxis, this will only work for printing the value, it will not change the value held by w

edited Mar 03 '13 at 18:35

answered Mar 03 '13 at 18:28

Tim

41,901
18
127
145

Correct for printing only. If he want 'w' to have only two decimals, he needs to round it ( int(100 * w)/100.0 ). – Synxis Mar 03 '13 at 18:31
1

That's true, but I figured this is what he needed – Tim Mar 03 '13 at 18:33
Makes sense since the line is right before the return statement. – Mike D Mar 03 '13 at 18:37
This is perfect. Thanks! Added this to the code here: https://compilr.com/timbogrocott/square/Square.cpp – Godzdude Mar 03 '13 at 19:20

score 2 · Answer 2 · answered Mar 03 '13 at 18:33

2

You can alway multiply your answer x by 100, round, and then divide by 100.

x = (int)(x*100+0.5f);  
x = ( (float)(x) ) / 100.0;

answered Mar 03 '13 at 18:33

namu

146
9

score 1 · Answer 3 · answered Mar 03 '13 at 19:06

You could change your monetary unit to "cents" and then divide by 100 to get the dollars and mod 100 to get the cents.

unsigned int money = 152; // USD $1.52

cout << "Money is: " << (money / 100) << "." << (money % 100) << "\n";

This may be more accurate. Search the web for "everything knows floating point".

Looking to round the final answer to 2 decimals C++

3 Answers3

Linked