1，代码先行

示例：

#include<iostream>
#include<limits>

using namespace std;

int main()
{
    float inf_pos = numeric_limits<float>::infinity();

    float inf_neg = -1*inf_pos;

    cout << "inf_pos = " << inf_pos << endl;
    cout << "inf_neg = " << inf_neg << endl;
    cout << "inf_pos + inf_neg = " << inf_pos + inf_neg << endl;
    cout << "1.0/0.0 = "<< 1.0/0.0 << endl;
    cout << "-1.0/0.0 = "<< -1.0/0.0 << endl;

    cout << "1/0 = "<< 1/0 << endl;
    cout << "-1/0 = "<< -1/0 << endl;
    return 0;
}

注意头文件 limits

2，运行

1.0/0.0 包含进了IEEE754，而1/0并没有，所以报错了