C++中的lrint()和llrint()

lrint()函数使用当前的舍入模式将自变量中给出的分数值舍入为整数值。
在这里，当前模式由函数fesetround()确定。

注意：此函数返回long int中的最终值。
句法：

lrint(double a);
lrint(float a);

Parameter:

The lrint() function takes double or float or integer value as an argument.

Return:

The lrint() function rounds the fractional value given in the argument to an integral value using the current rounding mode and return value in a long int. Here, the current mode is determined by the function fesetround(). By default, the rounding direction is set to ‘to-nearest’.
It can be changed using fesetround().

Error:

It is mandatory to give an argument otherwise it will give error no matching function for call to ‘lrint()’ like this.

＃代码1

// CPP code to illustrate
// the functionality of lrint()
#include 
#include 
#include 
using namespace std;
  
int main()
{
    int a = 15;
    long int answer;
  
    // setting rounding direction to DOWNWARD
    fesetround(FE_DOWNWARD);
    answer = lrint(a);
    cout << "Downward rounding of " << a 
         << " is " << answer << endl;
  
    return 0;
}

输出 ：

Downward rounding of 15 is 15

＃代码2

// CPP code to illustrate
// the functionality of lrint()
#include 
#include 
#include 
using namespace std;
  
int main()
{
    double a;
    long int answer;
  
    // By default, the rounding direction
    // is set to 'to-nearest'.
    // fesetround(FE_TONEAREST)
    a = 50.35;
    answer = lrint(a);
    cout << "Nearest rounding of " << a 
         << " is " << answer << endl;
  
    // mid values are rounded off to higher integer
    a = 50.5;
    answer = lrint(a);
    cout << "Nearest rounding of " << a 
         << " is " << answer << endl;
  
    return 0;
}

输出 ：

Nearest rounding of 50.35 is 50
Nearest rounding of 50.5 is 50

＃代码3

// CPP code to illustrate
// the functionality of lrint()
#include 
#include 
#include 
using namespace std;
  
int main()
{
    double a;
    long int answer;
  
    // Now, the rounding direction
    // is set to UPWARD
    fesetround(FE_UPWARD);
    a = 50.3;
    answer = lrint(a);
    cout << "Upward rounding of " << a 
         << " is " << answer << endl;
  
    // Now, the rounding direction
    //  is set to DOWNWARD
    fesetround(FE_DOWNWARD);
    a = 50.88;
    answer = lrint(a);
    cout << "Downward rounding of " << a 
         << " is " << answer << endl;
  
    return 0;
}

输出 ：

Upward rounding of 50.3 is 51
Downward rounding of 50.88 is 50

C++中的llrint()

llrint()函数使用当前的舍入模式将自变量中给出的分数值舍入为整数值。
在这里，当前模式由函数fesetround()确定。

注意：因此，函数以long long int返回值
句法：

llrint(double a);
llrint(float a);

Parameter:

The llrint() function takes double or float or integer value as an argument.

Return:

The llrint() function rounds the fractional value given in the argument to
an integral value using the current rounding mode and and return value in
long long int.
Here, the current mode is determined by the function fesetround().
By default, the rounding direction is set to ‘to-nearest’.
It can be changed using fesetround().

Error:

It is mandatory to give an argument otherwise it will give error no matching function for call to ‘llrint()’ like this.

＃代码1

// CPP code to illustrate
// the functionality of llrint()
#include 
#include 
#include 
using namespace std;
  
int main()
{
    int a = 15;
    long long int answer;
  
    // setting rounding direction to DOWNWARD
    fesetround(FE_DOWNWARD);
    answer = llrint(a);
    cout << "Downward rounding of " << a 
         << " is " << answer << endl;
  
    return 0;
}

输出 ：

Downward rounding of 15 is 15

＃代码2

// CPP code to illustrate
// the functionality of llrint()
#include 
#include 
#include 
using namespace std;
  
int main()
{
    double a;
    long long int answer;
  
    // By default, the rounding direction is 
    // set to 'to-nearest'. fesetround(FE_TONEAREST)
    a = 50.35;
    answer = llrint(a);
    cout << "Nearest rounding of " << a 
         << " is " << answer << endl;
  
    // mid values are rounded off to higher integer
    a = 50.5;
    answer = llrint(a);
    cout << "Nearest rounding of " << a 
         << " is " << answer << endl;
  
    return 0;
}

输出 ：

Nearest rounding of 50.35 is 50
Nearest rounding of 50.5 is 50

＃代码3

// CPP code to illustrate
// the functionality of llrint()
#include 
#include 
#include 
using namespace std;
  
int main()
{
    double a;
    long long int answer;
  
    // Now, the rounding direction
    // is set to UPWARD
    fesetround(FE_UPWARD);
    a = 50.3;
    answer = llrint(a);
    cout << "Upward rounding of " << a 
         << " is " << answer << endl;
  
    // Now, the rounding direction is set to DOWNWARD
    fesetround(FE_DOWNWARD);
    a = 50.88;
    answer = llrint(a);
    cout << "Downward rounding of " << a 
         << " is " << answer << endl;
  
    return 0;
}

输出 ：

Upward rounding of 50.3 is 51
Downward rounding of 50.88 is 50

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