为什么我的C++程序会产生无意义的数学

Why is my C++ program generating nonsense math?

本文关键字：无意义 我的 C++ 程序 为什么      更新时间：2023-10-16

我的程序在下面

#include <iostream>
using namespace std;
int main()
{
    int a;
    int b; 
    int c;
    double perimeter = (a + b + c);
    int s=0.5*(a + b + c);
    cout << "Enter three numbers for the lengths of a triangle with sides a, b, and c. The first number should be the smallest, and the last should be the longest.";
    cin >> a;
    cin >> b;
    cin >> c;
    cout << "Lengths " ;
    cout << a; 
    cout << " " ;
    cout << b; 
    cout << " ";
    cout << c;
    cout << "The perimeter of the triangle is ";
    cout << perimeter ;
    cout << "s equals " ;
    cout << s;
}

这是输出： 

Enter three numbers for the lengths of a triangle with sides a, b, and c.  The first number should be the smallest, and the last should be the longest.
1
2
3
Lengths 1 2 3
The perimeter of the triangle is 32061
s equals 16030

最后我检查了一下，1 + 2 + 3 不等于 32061。 发生了什么，我该如何解决这个问题？

//

我猜这是因为我没有正确的标题//（#somethingoranother）？
还是我还没有宣布？但我不知道怎么做。我记得使用 sqrt 作为函数查找过去的根，但没有

#include <iostream>
using namespace std;

    int main()
    {
    int a = 0;
    int b = 0; 
    int c = 0;
    double area = 0;
    double sqrt=0;

      cout << "Enter three numbers for the lengths of a triangle with sides a, b, and c.  The first number should be the smallest, and the last should ne the longest.";
      cin >> a;
      cin >> b;
      cin >> c;
    int perimeter = (a + b + c);
    int s=0.5*(a + b + c);
    area = sqrt ( s*(s - a)*(s - b)*(s - c) );

     cout << "The perimeter of the triangle is ";
      cout << perimeter ;
      cout << "." ;
      cout << " s equals " ;
      cout << s; 
      cout << ".  ";
      cout << "Area is ";
      cout << area;
    }

只是输入"area ="的长公式，但计算机似乎也不喜欢这样

试试下面的代码。perimeter和s计算需要在初始化三角形边的值后进行。

#include <iostream>
using namespace std;
int main()
{
    int a;
    int b; 
    int c;
    cout << "Enter three numbers for the lengths of a triangle with sides a, b, and c. The first number should be the smallest, and the last should be the longest.";
    cin >> a;
    cin >> b;
    cin >> c;
    cout << "Lengths " ;
    cout << a; 
    cout << " " ;
    cout << b; 
    cout << " ";
    cout << c;
    double perimeter = (a + b + c);
    int s=0.5*(a + b + c);
    cout << "The perimeter of the triangle is ";
    cout << perimeter ;
    cout << "s equals " ;
    cout << s;
}

您正在将未初始化的值相加。在对它们进行数学运算之前，您需要填写 a、b 和 c。现在你这样做的方式是导致随机值加在一起，这就是为什么你会得到无意义的结果。

将计算移动到程序中的适当位置：在你知道输入数字之后，但在打印出来之前：

cout << "Enter three numbers for the lengths of a triangle with sides a, b, and c.  The first number should be the smallest, and the last should be    the longest.";
cin >> a;
cin >> b;
cin >> c;
double perimeter = (a + b + c);
int s=0.5*(a + b + c);
cout << "Lengths " ;
...
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