C++数据类型之实型（浮点型）&科学计数法

 1 #include<iostream>
 2 using namespace std;
 3 
 4 int main() {
 5     //1、单精度  float
 6     //2、双精度  double
 7     //默认情况下，输出一个小数，会显示6位有效数字；若要精确显示需另配置，较麻烦
 8     float f1 = 3.14f;
 9 
10     cout << "f1 = " << f1 << endl;
11 
12     double d1 = 3.14;
13     cout << "d1 = " << d1 << endl;
14 
15     //统计float和double占用的内存空间
16     cout << "float  sizeof = " << sizeof(f1) << endl;
17     cout << "double sizeof = " << sizeof(d1) << endl;
18 
19     //科学计数法
20     float f2 = 3e2; //3*10^2
21     cout << "f2 = " << f2 << endl;
22 
23     float f3 = 3e-2; //3*0.1^2
24     cout << "f3 = " << f3 << endl;
25     system("pause");
26 
27     return 0;
28 }