如何在 C++ 中使用 setprecision
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How to use setprecision in C++
提问by Malik
I am new in C++, i just want to output my point number up to 2 digits.
just like if number is 3.444, then the output should be 3.44or if number is 99999.4234then output should be 99999.42, How can i do that. the value is dynamic. Here is my code.
我是新来的C++，我只想输出最多 2 位的点数。就像如果数字是3.444，那么输出应该是3.44或者如果数字是99999.4234那么输出应该是99999.42，我该怎么做。该值是动态的。这是我的代码。
#include <iomanip.h>
#include <iomanip>
int main()
{
double num1 = 3.12345678;
cout << fixed << showpoint;
cout << setprecision(2);
cout << num1 << endl;
}
but its giving me an error, undefined fixed symbol.
但它给了我一个错误，未定义的固定符号。
回答by piokuc
#include <iomanip>
#include <iostream>
int main()
{
double num1 = 3.12345678;
std::cout << std::fixed << std::showpoint;
std::cout << std::setprecision(2);
std::cout << num1 << std::endl;
return 0;
}
回答by Loyce
#include <iostream>
#include <iomanip>
using namespace std;
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 cout, fixed, showpoint, setprecision(2)and endl
using namespace std;为方便起见，您可以输入该行。否则，你必须明确地添加std::每次你想使用时间cout，fixed， showpoint，setprecision(2)和endl
int main()
{
double num1 = 3.12345678;
cout << fixed << showpoint;
cout << setprecision(2);
cout << num1 << endl;
return 0;
}
回答by aliasm2k
The answer above is absolutely correct. Here is a Turbo C++ version of it.
上面的答案是完全正确的。这是它的 Turbo C++ 版本。
#include <iomanip.h>
#include <iostream.h>
void main()
{
double num1 = 3.12345678;
cout << setiosflags(fixed) << setiosflags(showpoint);
cout << setprecision(2);
cout << num1 << endl;
}
For fixedand showpoint, I think the setiosflagsfunction should be used.
对于fixedand showpoint，我认为setiosflags应该使用该函数。
回答by aliasm2k
Replace These Headers
替换这些标题
#include <iomanip.h>
#include <iomanip>
With These.
用这些。
#include <iostream>
#include <iomanip>
using namespace std;
Thats it...!!!
就是这样...！！！
回答by user13461811
#include <bits/stdc++.h> // to include all libraries
using namespace std;
int main()
{
double a,b;
cin>>a>>b;
double x=a/b; //say we want to divide a/b
cout<<fixed<<setprecision(10)<<x; //for precision upto 10 digit
return 0;
}
/*input : 1987 31 output : 662.3333333333 10 digits after decimal point */
/*输入：1987 31 输出：662.3333333333 小数点后 10 位 */
回答by Pankaj Kumar Thapa
Below code runs correctly.
下面的代码运行正确。
#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
double num1 = 3.12345678;
cout << fixed << showpoint;
cout << setprecision(2);
cout << num1 << endl;
}
