C++ Tutorials

C++ Tutorials

You can enter the line using namespace std; for your convenience. Otherwise, you’ll have to explicitly add std:: every time you wish to use coutfixedshowpointsetprecision(2) and endl

#include <iostream>
#include <iomanip>

int main () {
   double f =3.14159;
   std::cout << std::setprecision(5) << f << '\n';
   std::cout << std::setprecision(9) << f << '\n';
   std::cout << std::fixed;
   std::cout << std::setprecision(5) << f << '\n';
   std::cout << std::setprecision(9) << f << '\n';
   return 0;
}

std::setprecision. /*unspecified*/ setprecision (int n);. Set decimal precision. Sets the decimal precision to be used to format floating-point values on output

C++ setprecision not working

You could #include <limits>, remove the step that gets the precision from input and change your code to:

std::cout << std::setprecision(std::numeric_limits<float>::max_digits10);

The answer above is absolutely correct. Here is a Turbo C++ version of it.

#include <iomanip.h>
#include <iostream.h>

void main()
{
    double num1 = 3.12345678;
    cout << setiosflags(fixed) << setiosflags(showpoint);
    cout << setprecision(2);
    cout << num1 << endl;
}

C++ setprecision without rounding

How to fixed number of digits in C++ without rounding

If you would like to truncate the value to two decimal places, you can multiply it by 100, truncate to integer, and then divide by 100, like this:

#include <iomanip.h>
#include <iostream.h>

void main()
{
c = a / b;
c = floor(100 * c) / 100;
cout<<"Result: "<<fixed<<setprecision(2)<<c<<endl;
return 0;
}

C++ round to two decimal places

Rounding Floating Point Number To two Decimal Places in C and C++. Difficulty Level : Medium. Round off a floatig point value to two places. Floating Point Operations & Associativity in C, C++

I know how to round off a number to only 2 decimal points? For example, 2.789 becomes 2.79
2.43 become 2.4

 I want to round a floating point numbers after 2 decimal places.
Ex–
float x=3.1459;
float y;

I want ro round ‘x’ up tp 2 decimal places and store it in ‘y’ so that y=3.15.

To round a double up to 2 decimal places, you can use:

#include <iostream>
#include <cmath>

int main() {
    double value = 0.123;
    value = std::ceil(value * 100.0) / 100.0;
    std::cout << value << std::endl; // prints 0.13
    return 0;
}

To round up to n decimal places, you can use:

double round_up(double value, int decimal_places) {
    const double multiplier = std::pow(10.0, decimal_places);
    return std::ceil(value * multiplier) / multiplier;
}

This method won’t be particularly fast, if performance becomes an issue you may need another solution.

How to limit decimal places in c++

The following code will solve your problem (limit decimal places in c++).

#include <iostream>

int main() {
	double d = 5.477225575051661134;
	float digit;
	double sc = 0.0001;
	digit = (int)(d/sc)*sc;
	std::cout << digit;
	return 0;
}
double scale = 0.01;  // i.e. round to nearest one-hundreth
value = (int)(value / scale) * scale;

or (rounding up/down as appropriate, per jheriko’s answer)

double scale = 0.01;  // i.e. round to nearest one-hundreth
value = floor(value / scale + 0.5) * scale;

For the latter:

cout << setprecision(2) << value;

where the parameter to setprecision() is the maximum number of digits to show after the decimal point.

C++ fixed

std::fixed – Fixed Floating-point notation : It write floating-point values in fixed-point notation. The fixed() method of stream manipulators in C++ is used to set the float field format flag for the specified str stream.

fixed() method of stream manipulators in C++ is used to set the floatfield format flag for the specified str stream. This flag sets the floatfield to fixed.

Showpoint c++

std::showpoint. ios_base& showpoint (ios_base& str);. Show decimal point. Sets the showpoint format flag for the str stream.

The showpoint() method of stream manipulators in C++ is used to set the showpoint format flag for the specified str stream.

C++ ios Library – Showpoint Function – It is used to sets the showpoint format flag for the str stream. When the showpoint format flag is set.

If the precision is 0 and showpoint is not used, no decimal-point appears, else it does appear:

#include <iostream>
#include <iomanip>

int
main()
{
    double pi = 2646693125139304345./842468587426513207.;
    std::cout << std::fixed << std::setprecision(0);
    std::cout << pi << '\n';
    std::cout << std::showpoint;
    std::cout << pi << '\n';
}

Should output:

3
3.