Exercise URI 1012 - Wrong answer 20%

[Kadyn]

I did the exercise, almost all outputs are coming out as the URI output are asking, but the first requirement is not as you ask in the program. I used setprecision, but I am in doubt because the first result does not round 3 decimal places after comma. a 3.0 b. c 5.2

TRIANGULO: 7.800
CIRCULO: 84.949
TRAPEZIO: 18.200
QUADRADO: 16.000
RETANGULO: 12.000

my first exit TRIANGULO leaves only 7.8 and the others leave perfectly.

#include <iostream>
#include <iomanip>
#include <math.h>
int main(int argc, char** argv)

{

double pi = 3.14159;

double a, b, c;

double area_triangulo, area_circulo, area_trapezio,

area_quadrado,area_retangulo;
std::cin &gt;&gt; a &gt;&gt; b &gt;&gt; c;

area_triangulo = a * c / 2;
area_circulo = pi * pow(c, 2);
area_trapezio = ((a + b)* c)/2;
area_quadrado = pow(b, 2);
area_retangulo = a * b;

std::cout &lt;&lt; "TRIANGULO: " &lt;&lt;area_triangulo &lt;&lt; std::setprecision(5)&lt;&lt;           
std::fixed &lt;&lt; std::endl;    
std::cout &lt;&lt; "CIRCULO: " &lt;&lt;area_circulo &lt;&lt; std::setprecision(3)&lt;&lt; 
std::fixed &lt;&lt; std::endl;    
std::cout &lt;&lt; "TRAPEZIO: " &lt;&lt;area_trapezio &lt;&lt; std::setprecision(3)&lt;&lt; 
std::fixed &lt;&lt; std::endl;
std::cout &lt;&lt; "QUADRADO: " &lt;&lt;area_quadrado &lt;&lt; std::setprecision(3)&lt;&lt; 
std::fixed &lt;&lt; std::endl;
std::cout &lt;&lt; "RETANGULO: " &lt;&lt;area_retangulo &lt;&lt; std::setprecision(3)&lt;&lt; 
std::fixed &lt;&lt; std::endl;

return 0;

}

[amarantha]

O http://www.cplusplus.com/reference/ios/fixed/ indicates that the following writings will be made with fixed point notation. The amount of digits shown after the crankshaft is set with http://www.cplusplus.com/reference/iomanip/setprecision/ .

If you want to show 3 digits after the wig you must use:

std::setprecision(3);

You must use std::fixed and set::setprecision before writing any numerical output and only once:

std::cout << std::fixed << std::setprecision(3);
std::cout << "TRIANGULO: " <<area_triangulo << std::endl;
std::cout << "CIRCULO: " <<area_circulo << std::endl;
std::cout << "TRAPEZIO: " <<area_trapezio << std::endl;
std::cout << "QUADRADO: " <<area_quadrado << std::endl;
std::cout << "RETANGULO: " <<area_retangulo << std::endl;

https://ideone.com/P9bEN3