C++에서 절대값을 표현하는 방법

<code class="cpp">#include <cmath>

double abs(double x);
float abs(float x);
long double abs(long double x);</code>

<code class="cpp">#include <iostream>
#include <cmath>

using namespace std;

int main() {
  double x = -5.0;
  cout << "绝对值：" << abs(x) << endl;  // 输出：5

  float y = -1.234f;
  cout << "绝对值：" << abs(y) << endl;  // 输出：1.234

  long double z = -1234567890123.4567890123456789L;
  cout << "绝对值：" << abs(z) << endl;  // 输出：1234567890123.4567890123456789
}</code>