round()C ++中的函数用于将作为参数传递给它的double，float或long double值四舍五入到最接近的整数值。在c ++程序中用于使用round()函数的头文件是<cmath>或<tgmath>。
以下是round()C ++ 11标准之后的重载版本
双轮（双D）
圆浮（F浮）
长双圆（长双LD）
双轮（T var）
注–返回的值是表示为浮点数的最接近的整数，即对于2.3，返回的最接近的值将是2.0而不是2。
以下程序用于演示C ++程序中round函数的用法-
#include <cmath>
#include <iostream>
int main(){
double num1=10.5;
double num2=10.3;
double num3=9.7;
std::cout << "Nearest integer after round("<<num1<<") :" << round(num1)<< "\n";
std::cout << "Nearest integer after round("<<num2<<") :" << round(num2)<< "\n";
std::cout << "Nearest integer after round("<<num3<<") :" << round(num3)<< "\n";
num1=-9.3;
num2=-0.3;
num3=-9.9;
std::cout << "Nearest integer after round("<<num1<<") :" << round(num1)<< "\n";
std::cout << "Nearest integer after round("<<num2<<") :" << round(num2)<< "\n";
std::cout << "Nearest integer after round("<<num3<<") :" << round(num3)<< "\n";
return 0;
}输出结果
Nearest integer after round(10.5) :11 Nearest integer after round(10.3) :10 Nearest integer after round(9.7) :10 Nearest integer after round(-9.3) :-9 Nearest integer after round(-0.3) :-0 Nearest integer after round(-9.9) :-10