为什么我的计算器不响应我的 if 语句？
Why is my calculator not responding to my if statements?
这里是新手程序员。我完成了我正在处理的这个项目，并且我的所有 if 和 else 语句都正常运行，但只有当它们被放置在我正在编写的代码的最顶部时。
例如，我从 if(number == 1) 开始编写这段代码，然后一路往下写，但我最终不得不将它们剪切并粘贴到顶部，因为当我输入的值不是 1 (第一个 if 语句，因此是起作用的 top 语句），计算器在输入除顶部以外的任何其他值时根本无法打印任何内容。因为 4 在顶部，所以它可以正常工作，但是 1-3 不起作用，如果我将 1 放在顶部，那么 2-4 将不会打印任何内容。
下面是底部的 if 语句的屏幕截图，没有打印，也没有调试标志：
我确定这是一个小问题，我设法把它变成了大问题。
#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
int number;
float area1, area2, area3, area4;
int R1;
int trib;
int trih;
int top;
int bott;
int traph;
int majxis;
int minxis;
const float PI= 3.14159;
cout<< "I'm starting my program ";
cout<<"\n1.Circle";
cout<<"\n2.triangle";
cout<<"\n3.trapezoid";
cout<<"\n4.ellipse ";
cout<<"\nEnter the corresponding number of your choice(1-4):";
cin>> number;
if(number <= 0)
{
cout<<"Integer is invalid, try again ";
cin>> number;
}
if(number == 4)
{
cout<<"\nWhat is the length of the semi-major axis of the ellipse? ";
}
cin>> majxis;
if(majxis <=0)
{
cout<<"Invalid value for the semi-major axis, try again: ";
}
else
{
cout<<"What is the length for the semi-minor axis of the ellipse? ";
}
cin>> minxis;
area4= PI*minxis*majxis;
if(minxis <=0)
{
cout<<"Invalid value for the semi-minor axis, try again: ";
}
else
{
cout<<"The area of an ellipse with a semi-major axis of " << majxis<< "and a semi-minor axis of " << minxis << "is " << area4;
}
if(number == 3)
{
cout<<"\nWhat is the length of the top of the trapezoid? ";
}
cin>> top;
if(top <=0 )
{
cout<<"\n Invalid value for top length of trapezoid, try again";
}
else
{
cout<<"\nWhat is the length of the bottom of the trapezoid? ";
}
cin>> bott;
if (bott <= 0)
{
cout<<"Invalid value for bottom length of trapezoid, try again: ";
}
else
{
cout<<"What is the height of the trapezoid? ";
}
cin>>traph;
area3 = (top+bott)*0.5+traph;
if (traph <= 0)
{
cout<<"Invalid value for height of trapezoid";
}
else
{
cout<<"The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area3;
}
if(number == 2)
{
cout<<"\nWhat is the length of the base of the triangle?";
}
cin>> trib;
if(trib<=0)
{
cout<<"\nInvalid Base of triangle, try again:";
}
else
{
cout<<"\nWhat is the height of the triangle? ";
}
cin>> trih;
area2 = (0.5*trib)*trih;
if(trih<=0)
{
cout<<"\nInvalid height of triangle, try again:";
}
else
{
cout<<"\nThe area of a trangle with a base of " << trib << "and a height of "<< trih <<" is " << area2;
}
if(number == 1)
{
cout<<"\nWhat is the radius of the circle?";
}
cin>> R1;
area1 = PI*(R1 *R1);
if( R1 <=0)
{cout<<"\nRadius must be greater than 0, try again";
cin>> R1;
}
else
{
cout<< "\nThe area of a circle with a radius of " << R1 << " is" << area1;
}
}
确实是个小问题。这是正确的程序：
#include <iostream>
#include <iomanip>
int main()
{
int number;
float area1, area2, area3, area4;
int R1;
int trib;
int trih;
int top;
int bott;
int traph;
int majxis;
int minxis;
const float PI = 3.14159;
std::cout << "I'm starting my program ";
std::cout << "\n1.Circle";
std::cout << "\n2.triangle";
std::cout << "\n3.trapezoid";
std::cout << "\n4.ellipse ";
std::cout << "\nEnter the corresponding number of your choice(1-4):";
std::cin >> number;
if (number <= 0)
{
std::cout << "Integer is invalid, try again ";
std::cin >> number;
}
else if (number == 1)
{
std::cout << "\nWhat is the radius of the circle?";
std::cin >> R1;
area1 = PI * (R1 * R1);
if (R1 <= 0)
{
std::cout << "\nRadius must be greater than 0, try again";
std::cin >> R1;
}
else
{
std::cout << "\nThe area of a circle with a radius of " << R1 << " is" << area1;
}
}
else if (number == 2)
{
std::cout << "\nWhat is the length of the base of the triangle?";
std::cin >> trib;
if (trib <= 0)
{
std::cout << "\nInvalid Base of triangle, try again:";
}
else
{
std::cout << "\nWhat is the height of the triangle? ";
}
std::cin >> trih;
area2 = (0.5 * trib) * trih;
if (trih <= 0)
{
std::cout << "\nInvalid height of triangle, try again:";
}
else
{
std::cout << "\nThe area of a trangle with a base of " << trib << "and a height of " << trih << " is " << area2;
}
}
else if (number == 3)
{
std::cout << "\nWhat is the length of the top of the trapezoid? ";
std::cin >> top;
if (top <= 0)
{
std::cout << "\n Invalid value for top length of trapezoid, try again";
}
else
{
std::cout << "\nWhat is the length of the bottom of the trapezoid? ";
}
std::cin >> bott;
if (bott <= 0)
{
std::cout << "Invalid value for bottom length of trapezoid, try again: ";
}
else
{
std::cout << "What is the height of the trapezoid? ";
}
std::cin >> traph;
area3 = (top + bott) * 0.5 + traph;
if (traph <= 0)
{
std::cout << "Invalid value for height of trapezoid";
}
else
{
std::cout << "The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area3;
}
}
else if (number == 4)
{
std::cout << "\nWhat is the length of the semi-major axis of the ellipse? ";
std::cin >> majxis;
if (majxis <= 0)
{
std::cout << "Invalid value for the semi-major axis, try again: ";
}
else
{
std::cout << "What is the length for the semi-minor axis of the ellipse? ";
}
std::cin >> minxis;
area4 = PI * minxis * majxis;
if (minxis <= 0)
{
std::cout << "Invalid value for the semi-minor axis, try again: ";
}
else
{
std::cout << "The area of an ellipse with a semi-major axis of " << majxis << "and a semi-minor axis of " << minxis << "is " << area4;
}
}
}
解释：我们以eclipse的区域（number == 4）为例。在你的代码中，你做了以下 if 条件：
if(number == 4)
{
cout<<"\nWhat is the length of the semi-major axis of the ellipse? ";
}
这意味着 if number == 4 then print - "\n椭圆的 semi-major 轴的长度是多少？" 但它之后的所有代码都在 if 条件的 {} 括号之外，因此不被视为 if 语句的一部分。即使数字 != 4，它也会被调用。现在，在我的代码中，我已经这样做了：
else if (number == 4)
{
std::cout << "\nWhat is the length of the semi-major axis of the ellipse? ";
std::cin >> majxis;
if (majxis <= 0)
{
std::cout << "Invalid value for the semi-major axis, try again: ";
}
else
{
std::cout << "What is the length for the semi-minor axis of the ellipse? ";
}
std::cin >> minxis;
area4 = PI * minxis * majxis;
if (minxis <= 0)
{
std::cout << "Invalid value for the semi-minor axis, try again: ";
}
else
{
std::cout << "The area of an ellipse with a semi-major axis of " << majxis << "and a semi-minor axis of " << minxis << "is " << area4;
}
}
在这里，所有与eclipse区域相关的代码都是if (number == 4)语句的一部分，因为它存在于if (number == 4)语句的括号{}之间.
将此应用于所有 4 种情况，您将获得正确的程序。
此外，最好重构你的代码：
#include <iostream>
#include <iomanip>
const float PI = 3.14159;
void areaof_circle()
{
float area;
int R1;
std::cout << "\nWhat is the radius of the circle?";
std::cin >> R1;
area = PI * (R1 * R1);
if (R1 <= 0)
{
std::cout << "\nRadius must be greater than 0, try again";
std::cin >> R1;
}
else
{
std::cout << "\nThe area of a circle with a radius of " << R1 << " is" << area;
}
}
void areaof_triangle()
{
float area;
int trib, trih;
std::cout << "\nWhat is the length of the base of the triangle?";
std::cin >> trib;
if (trib <= 0)
{
std::cout << "\nInvalid Base of triangle, try again:";
}
else
{
std::cout << "\nWhat is the height of the triangle? ";
}
std::cin >> trih;
area = (0.5 * trib) * trih;
if (trih <= 0)
{
std::cout << "\nInvalid height of triangle, try again:";
}
else
{
std::cout << "\nThe area of a trangle with a base of " << trib << "and a height of " << trih << " is " << area;
}
}
void areaof_trapezoid()
{
float area;
int top, bott, traph;
std::cout << "\nWhat is the length of the top of the trapezoid? ";
std::cin >> top;
if (top <= 0)
{
std::cout << "\n Invalid value for top length of trapezoid, try again";
}
else
{
std::cout << "\nWhat is the length of the bottom of the trapezoid? ";
}
std::cin >> bott;
if (bott <= 0)
{
std::cout << "Invalid value for bottom length of trapezoid, try again: ";
}
else
{
std::cout << "What is the height of the trapezoid? ";
}
std::cin >> traph;
area = (top + bott) * 0.5 + traph;
if (traph <= 0)
{
std::cout << "Invalid value for height of trapezoid";
}
else
{
std::cout << "The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area;
}
}
void areaof_ellipse()
{
float area;
int majxis, minxis;
std::cout << "\nWhat is the length of the semi-major axis of the ellipse? ";
std::cin >> majxis;
if (majxis <= 0)
{
std::cout << "Invalid value for the semi-major axis, try again: ";
}
else
{
std::cout << "What is the length for the semi-minor axis of the ellipse? ";
}
std::cin >> minxis;
area = PI * minxis * majxis;
if (minxis <= 0)
{
std::cout << "Invalid value for the semi-minor axis, try again: ";
}
else
{
std::cout << "The area of an ellipse with a semi-major axis of " << majxis << "and a semi-minor axis of " << minxis << "is " << area;
}
}
int main()
{
int number;
const float PI = 3.14159;
std::cout << "I'm starting my program ";
std::cout << "\n1.Circle";
std::cout << "\n2.triangle";
std::cout << "\n3.trapezoid";
std::cout << "\n4.ellipse ";
std::cout << "\nEnter the corresponding number of your choice(1-4):";
std::cin >> number;
if (number <= 0)
{
std::cout << "Integer is invalid, try again ";
std::cin >> number;
}
else if (number == 1)
{
areaof_circle();
}
else if (number == 2)
{
areaof_triangle();
}
else if (number == 3)
{
areaof_trapezoid();
}
else if (number == 4)
{
areaof_ellipse();
}
}
此外，请勿在您的程序中使用以下内容：
using namespace std;
...因为它被认为是不好的做法。每次都使用 std::。
你的 if 语句有问题..
由于已经给出了定义明确的答案，我正在简化您的代码的可读性并建议更好的方法来做到这一点..
注意：考虑到你是新手。
创建函数来处理不同的四边形
#include <iostream>
#include <iomanip>
using namespace std;
float area1, area2, area3, area4;
int R1;
int trib;
int trih;
int top;
int bott;
int traph;
int majxis;
int minxis;
const float PI= 3.14159;
void handle_circle();
void handle_ellipse();
void handle_triangle();
void handle_trapizoid();
int main()
{
int number;
cout<< "I'm starting my program ";
cout<<"\n1.Circle";
cout<<"\n2.triangle";
cout<<"\n3.trapezoid";
cout<<"\n4.ellipse ";
cout<<"\nEnter the corresponding number of your choice(1-4):";
cin>> number;
if(number <= 0)
{
cout<<"Integer is invalid, try again ";
cin>> number;
}
if(number == 4)
{
handle_ellipse();
}
if(number == 3)
{
handle_trapizoid();
}
if(number == 2)
{
handle_triangle();
}
if(number == 1)
{
handle_circle();
}
}
void handle_trapizoid()
{
cout<<"\nWhat is the length of the top of the trapezoid? ";
cin>> top;
if(top <=0 )
{
cout<<"\n Invalid value for top length of trapezoid, try again";
}
else
{
cout<<"\nWhat is the length of the bottom of the trapezoid? ";
cin>> bott;
}
if (bott <= 0)
{
cout<<"Invalid value for bottom length of trapezoid, try again: ";
}
else
{
cout<<"What is the height of the trapezoid? ";
cin>>traph;
area3 = (top+bott)*0.5+traph;
}
if (traph <= 0)
{
cout<<"Invalid value for height of trapezoid";
}
else
{
cout<<"The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area3;
}
}
void handle_ellipse()
{
cout<<"\nWhat is the length of the semi-major axis of the ellipse? ";
cin>> majxis;
if(majxis <=0)
{
cout<<"Invalid value for the semi-major axis, try again: ";
}
else
{
cout<<"What is the length for the semi-minor axis of the ellipse? ";
cin>> minxis;
area4= PI*minxis*majxis;
}
if(minxis <=0)
{
cout<<"Invalid value for the semi-minor axis, try again: ";
}
else
{
cout<<"The area of an ellipse with a semi-major axis of " << majxis<< "and a semi-minor axis of " << minxis << "is " << area4;
}
}
void handle_triangle()
{
cout<<"\nWhat is the length of the base of the triangle?";
cin>> trib;
if(trib<=0)
{
cout<<"\nInvalid Base of triangle, try again:";
}
else
{
cout<<"\nWhat is the height of the triangle? ";
cin>> trih;
area2 = (0.5*trib)*trih;
}
if(trih<=0)
{
cout<<"\nInvalid height of triangle, try again:";
}
else
{
cout<<"\nThe area of a trangle with a base of " << trib << "and a height of "<< trih <<" is " << area2;
}
}
void handle_circle()
{
cout<<"\nWhat is the radius of the circle?";
cin>> R1;
area1 = PI*(R1 *R1);
if( R1 <=0)
{cout<<"\nRadius must be greater than 0, try again";
cin>> R1;
}
else
{
cout<< "\nThe area of a circle with a radius of " << R1 << " is" << area1;
}
}
您也可以使用 switch 语句，因为它比 if 语句更快
#include <iostream>
#include <iomanip>
using namespace std;
float area1, area2, area3, area4;
int R1;
int trib;
int trih;
int top;
int bott;
int traph;
int majxis;
int minxis;
const float PI= 3.14159;
void handle_circle();
void handle_ellipse();
void handle_triangle();
void handle_trapizoid();
int main()
{
int number;
cout<< "I'm starting my program ";
cout<<"\n1.Circle";
cout<<"\n2.triangle";
cout<<"\n3.trapezoid";
cout<<"\n4.ellipse ";
cout<<"\nEnter the corresponding number of your choice(1-4):";
cin>> number;
switch(number)
{
case 1:
handle_circle();
break;
case 2:
handle_triangle();
break;
case 3:
handle_ellipse();
break;
case 4:
handle_trapizoid();
break;
default:
{
cout<<"Integer is invalid, try again ";
}
}
}
void handle_trapizoid()
{
cout<<"\nWhat is the length of the top of the trapezoid? ";
cin>> top;
if(top <=0 )
{
cout<<"\n Invalid value for top length of trapezoid, try again";
}
else
{
cout<<"\nWhat is the length of the bottom of the trapezoid? ";
cin>> bott;
}
if (bott <= 0)
{
cout<<"Invalid value for bottom length of trapezoid, try again: ";
}
else
{
cout<<"What is the height of the trapezoid? ";
cin>>traph;
area3 = (top+bott)*0.5+traph;
}
if (traph <= 0)
{
cout<<"Invalid value for height of trapezoid";
}
else
{
cout<<"The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area3;
}
}
void handle_ellipse()
{
cout<<"\nWhat is the length of the semi-major axis of the ellipse? ";
cin>> majxis;
if(majxis <=0)
{
cout<<"Invalid value for the semi-major axis, try again: ";
}
else
{
cout<<"What is the length for the semi-minor axis of the ellipse? ";
cin>> minxis;
area4= PI*minxis*majxis;
}
if(minxis <=0)
{
cout<<"Invalid value for the semi-minor axis, try again: ";
}
else
{
cout<<"The area of an ellipse with a semi-major axis of " << majxis<< "and a semi-minor axis of " << minxis << "is " << area4;
}
}
void handle_triangle()
{
cout<<"\nWhat is the length of the base of the triangle?";
cin>> trib;
if(trib<=0)
{
cout<<"\nInvalid Base of triangle, try again:";
}
else
{
cout<<"\nWhat is the height of the triangle? ";
cin>> trih;
area2 = (0.5*trib)*trih;
}
if(trih<=0)
{
cout<<"\nInvalid height of triangle, try again:";
}
else
{
cout<<"\nThe area of a trangle with a base of " << trib << "and a height of "<< trih <<" is " << area2;
}
}
void handle_circle()
{
cout<<"\nWhat is the radius of the circle?";
cin>> R1;
area1 = PI*(R1 *R1);
if( R1 <=0)
{cout<<"\nRadius must be greater than 0, try again";
cin>> R1;
}
else
{
cout<< "\nThe area of a circle with a radius of " << R1 << " is" << area1;
}
}
这里是新手程序员。我完成了我正在处理的这个项目，并且我的所有 if 和 else 语句都正常运行，但只有当它们被放置在我正在编写的代码的最顶部时。
例如，我从 if(number == 1) 开始编写这段代码，然后一路往下写，但我最终不得不将它们剪切并粘贴到顶部，因为当我输入的值不是 1 (第一个 if 语句，因此是起作用的 top 语句），计算器在输入除顶部以外的任何其他值时根本无法打印任何内容。因为 4 在顶部，所以它可以正常工作，但是 1-3 不起作用，如果我将 1 放在顶部，那么 2-4 将不会打印任何内容。
下面是底部的 if 语句的屏幕截图，没有打印，也没有调试标志：
我确定这是一个小问题，我设法把它变成了大问题。
#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
int number;
float area1, area2, area3, area4;
int R1;
int trib;
int trih;
int top;
int bott;
int traph;
int majxis;
int minxis;
const float PI= 3.14159;
cout<< "I'm starting my program ";
cout<<"\n1.Circle";
cout<<"\n2.triangle";
cout<<"\n3.trapezoid";
cout<<"\n4.ellipse ";
cout<<"\nEnter the corresponding number of your choice(1-4):";
cin>> number;
if(number <= 0)
{
cout<<"Integer is invalid, try again ";
cin>> number;
}
if(number == 4)
{
cout<<"\nWhat is the length of the semi-major axis of the ellipse? ";
}
cin>> majxis;
if(majxis <=0)
{
cout<<"Invalid value for the semi-major axis, try again: ";
}
else
{
cout<<"What is the length for the semi-minor axis of the ellipse? ";
}
cin>> minxis;
area4= PI*minxis*majxis;
if(minxis <=0)
{
cout<<"Invalid value for the semi-minor axis, try again: ";
}
else
{
cout<<"The area of an ellipse with a semi-major axis of " << majxis<< "and a semi-minor axis of " << minxis << "is " << area4;
}
if(number == 3)
{
cout<<"\nWhat is the length of the top of the trapezoid? ";
}
cin>> top;
if(top <=0 )
{
cout<<"\n Invalid value for top length of trapezoid, try again";
}
else
{
cout<<"\nWhat is the length of the bottom of the trapezoid? ";
}
cin>> bott;
if (bott <= 0)
{
cout<<"Invalid value for bottom length of trapezoid, try again: ";
}
else
{
cout<<"What is the height of the trapezoid? ";
}
cin>>traph;
area3 = (top+bott)*0.5+traph;
if (traph <= 0)
{
cout<<"Invalid value for height of trapezoid";
}
else
{
cout<<"The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area3;
}
if(number == 2)
{
cout<<"\nWhat is the length of the base of the triangle?";
}
cin>> trib;
if(trib<=0)
{
cout<<"\nInvalid Base of triangle, try again:";
}
else
{
cout<<"\nWhat is the height of the triangle? ";
}
cin>> trih;
area2 = (0.5*trib)*trih;
if(trih<=0)
{
cout<<"\nInvalid height of triangle, try again:";
}
else
{
cout<<"\nThe area of a trangle with a base of " << trib << "and a height of "<< trih <<" is " << area2;
}
if(number == 1)
{
cout<<"\nWhat is the radius of the circle?";
}
cin>> R1;
area1 = PI*(R1 *R1);
if( R1 <=0)
{cout<<"\nRadius must be greater than 0, try again";
cin>> R1;
}
else
{
cout<< "\nThe area of a circle with a radius of " << R1 << " is" << area1;
}
}
确实是个小问题。这是正确的程序：
#include <iostream>
#include <iomanip>
int main()
{
int number;
float area1, area2, area3, area4;
int R1;
int trib;
int trih;
int top;
int bott;
int traph;
int majxis;
int minxis;
const float PI = 3.14159;
std::cout << "I'm starting my program ";
std::cout << "\n1.Circle";
std::cout << "\n2.triangle";
std::cout << "\n3.trapezoid";
std::cout << "\n4.ellipse ";
std::cout << "\nEnter the corresponding number of your choice(1-4):";
std::cin >> number;
if (number <= 0)
{
std::cout << "Integer is invalid, try again ";
std::cin >> number;
}
else if (number == 1)
{
std::cout << "\nWhat is the radius of the circle?";
std::cin >> R1;
area1 = PI * (R1 * R1);
if (R1 <= 0)
{
std::cout << "\nRadius must be greater than 0, try again";
std::cin >> R1;
}
else
{
std::cout << "\nThe area of a circle with a radius of " << R1 << " is" << area1;
}
}
else if (number == 2)
{
std::cout << "\nWhat is the length of the base of the triangle?";
std::cin >> trib;
if (trib <= 0)
{
std::cout << "\nInvalid Base of triangle, try again:";
}
else
{
std::cout << "\nWhat is the height of the triangle? ";
}
std::cin >> trih;
area2 = (0.5 * trib) * trih;
if (trih <= 0)
{
std::cout << "\nInvalid height of triangle, try again:";
}
else
{
std::cout << "\nThe area of a trangle with a base of " << trib << "and a height of " << trih << " is " << area2;
}
}
else if (number == 3)
{
std::cout << "\nWhat is the length of the top of the trapezoid? ";
std::cin >> top;
if (top <= 0)
{
std::cout << "\n Invalid value for top length of trapezoid, try again";
}
else
{
std::cout << "\nWhat is the length of the bottom of the trapezoid? ";
}
std::cin >> bott;
if (bott <= 0)
{
std::cout << "Invalid value for bottom length of trapezoid, try again: ";
}
else
{
std::cout << "What is the height of the trapezoid? ";
}
std::cin >> traph;
area3 = (top + bott) * 0.5 + traph;
if (traph <= 0)
{
std::cout << "Invalid value for height of trapezoid";
}
else
{
std::cout << "The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area3;
}
}
else if (number == 4)
{
std::cout << "\nWhat is the length of the semi-major axis of the ellipse? ";
std::cin >> majxis;
if (majxis <= 0)
{
std::cout << "Invalid value for the semi-major axis, try again: ";
}
else
{
std::cout << "What is the length for the semi-minor axis of the ellipse? ";
}
std::cin >> minxis;
area4 = PI * minxis * majxis;
if (minxis <= 0)
{
std::cout << "Invalid value for the semi-minor axis, try again: ";
}
else
{
std::cout << "The area of an ellipse with a semi-major axis of " << majxis << "and a semi-minor axis of " << minxis << "is " << area4;
}
}
}
解释：我们以eclipse的区域（number == 4）为例。在你的代码中，你做了以下 if 条件：
if(number == 4)
{
cout<<"\nWhat is the length of the semi-major axis of the ellipse? ";
}
这意味着 if number == 4 then print - "\n椭圆的 semi-major 轴的长度是多少？" 但它之后的所有代码都在 if 条件的 {} 括号之外，因此不被视为 if 语句的一部分。即使数字 != 4，它也会被调用。现在，在我的代码中，我已经这样做了：
else if (number == 4)
{
std::cout << "\nWhat is the length of the semi-major axis of the ellipse? ";
std::cin >> majxis;
if (majxis <= 0)
{
std::cout << "Invalid value for the semi-major axis, try again: ";
}
else
{
std::cout << "What is the length for the semi-minor axis of the ellipse? ";
}
std::cin >> minxis;
area4 = PI * minxis * majxis;
if (minxis <= 0)
{
std::cout << "Invalid value for the semi-minor axis, try again: ";
}
else
{
std::cout << "The area of an ellipse with a semi-major axis of " << majxis << "and a semi-minor axis of " << minxis << "is " << area4;
}
}
在这里，所有与eclipse区域相关的代码都是if (number == 4)语句的一部分，因为它存在于if (number == 4)语句的括号{}之间.
将此应用于所有 4 种情况，您将获得正确的程序。
此外，最好重构你的代码：
#include <iostream>
#include <iomanip>
const float PI = 3.14159;
void areaof_circle()
{
float area;
int R1;
std::cout << "\nWhat is the radius of the circle?";
std::cin >> R1;
area = PI * (R1 * R1);
if (R1 <= 0)
{
std::cout << "\nRadius must be greater than 0, try again";
std::cin >> R1;
}
else
{
std::cout << "\nThe area of a circle with a radius of " << R1 << " is" << area;
}
}
void areaof_triangle()
{
float area;
int trib, trih;
std::cout << "\nWhat is the length of the base of the triangle?";
std::cin >> trib;
if (trib <= 0)
{
std::cout << "\nInvalid Base of triangle, try again:";
}
else
{
std::cout << "\nWhat is the height of the triangle? ";
}
std::cin >> trih;
area = (0.5 * trib) * trih;
if (trih <= 0)
{
std::cout << "\nInvalid height of triangle, try again:";
}
else
{
std::cout << "\nThe area of a trangle with a base of " << trib << "and a height of " << trih << " is " << area;
}
}
void areaof_trapezoid()
{
float area;
int top, bott, traph;
std::cout << "\nWhat is the length of the top of the trapezoid? ";
std::cin >> top;
if (top <= 0)
{
std::cout << "\n Invalid value for top length of trapezoid, try again";
}
else
{
std::cout << "\nWhat is the length of the bottom of the trapezoid? ";
}
std::cin >> bott;
if (bott <= 0)
{
std::cout << "Invalid value for bottom length of trapezoid, try again: ";
}
else
{
std::cout << "What is the height of the trapezoid? ";
}
std::cin >> traph;
area = (top + bott) * 0.5 + traph;
if (traph <= 0)
{
std::cout << "Invalid value for height of trapezoid";
}
else
{
std::cout << "The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area;
}
}
void areaof_ellipse()
{
float area;
int majxis, minxis;
std::cout << "\nWhat is the length of the semi-major axis of the ellipse? ";
std::cin >> majxis;
if (majxis <= 0)
{
std::cout << "Invalid value for the semi-major axis, try again: ";
}
else
{
std::cout << "What is the length for the semi-minor axis of the ellipse? ";
}
std::cin >> minxis;
area = PI * minxis * majxis;
if (minxis <= 0)
{
std::cout << "Invalid value for the semi-minor axis, try again: ";
}
else
{
std::cout << "The area of an ellipse with a semi-major axis of " << majxis << "and a semi-minor axis of " << minxis << "is " << area;
}
}
int main()
{
int number;
const float PI = 3.14159;
std::cout << "I'm starting my program ";
std::cout << "\n1.Circle";
std::cout << "\n2.triangle";
std::cout << "\n3.trapezoid";
std::cout << "\n4.ellipse ";
std::cout << "\nEnter the corresponding number of your choice(1-4):";
std::cin >> number;
if (number <= 0)
{
std::cout << "Integer is invalid, try again ";
std::cin >> number;
}
else if (number == 1)
{
areaof_circle();
}
else if (number == 2)
{
areaof_triangle();
}
else if (number == 3)
{
areaof_trapezoid();
}
else if (number == 4)
{
areaof_ellipse();
}
}
此外，请勿在您的程序中使用以下内容：
using namespace std;
...因为它被认为是不好的做法。每次都使用 std::。
你的 if 语句有问题.. 由于已经给出了定义明确的答案，我正在简化您的代码的可读性并建议更好的方法来做到这一点..
注意：考虑到你是新手。
创建函数来处理不同的四边形
#include <iostream>
#include <iomanip>
using namespace std;
float area1, area2, area3, area4;
int R1;
int trib;
int trih;
int top;
int bott;
int traph;
int majxis;
int minxis;
const float PI= 3.14159;
void handle_circle();
void handle_ellipse();
void handle_triangle();
void handle_trapizoid();
int main()
{
int number;
cout<< "I'm starting my program ";
cout<<"\n1.Circle";
cout<<"\n2.triangle";
cout<<"\n3.trapezoid";
cout<<"\n4.ellipse ";
cout<<"\nEnter the corresponding number of your choice(1-4):";
cin>> number;
if(number <= 0)
{
cout<<"Integer is invalid, try again ";
cin>> number;
}
if(number == 4)
{
handle_ellipse();
}
if(number == 3)
{
handle_trapizoid();
}
if(number == 2)
{
handle_triangle();
}
if(number == 1)
{
handle_circle();
}
}
void handle_trapizoid()
{
cout<<"\nWhat is the length of the top of the trapezoid? ";
cin>> top;
if(top <=0 )
{
cout<<"\n Invalid value for top length of trapezoid, try again";
}
else
{
cout<<"\nWhat is the length of the bottom of the trapezoid? ";
cin>> bott;
}
if (bott <= 0)
{
cout<<"Invalid value for bottom length of trapezoid, try again: ";
}
else
{
cout<<"What is the height of the trapezoid? ";
cin>>traph;
area3 = (top+bott)*0.5+traph;
}
if (traph <= 0)
{
cout<<"Invalid value for height of trapezoid";
}
else
{
cout<<"The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area3;
}
}
void handle_ellipse()
{
cout<<"\nWhat is the length of the semi-major axis of the ellipse? ";
cin>> majxis;
if(majxis <=0)
{
cout<<"Invalid value for the semi-major axis, try again: ";
}
else
{
cout<<"What is the length for the semi-minor axis of the ellipse? ";
cin>> minxis;
area4= PI*minxis*majxis;
}
if(minxis <=0)
{
cout<<"Invalid value for the semi-minor axis, try again: ";
}
else
{
cout<<"The area of an ellipse with a semi-major axis of " << majxis<< "and a semi-minor axis of " << minxis << "is " << area4;
}
}
void handle_triangle()
{
cout<<"\nWhat is the length of the base of the triangle?";
cin>> trib;
if(trib<=0)
{
cout<<"\nInvalid Base of triangle, try again:";
}
else
{
cout<<"\nWhat is the height of the triangle? ";
cin>> trih;
area2 = (0.5*trib)*trih;
}
if(trih<=0)
{
cout<<"\nInvalid height of triangle, try again:";
}
else
{
cout<<"\nThe area of a trangle with a base of " << trib << "and a height of "<< trih <<" is " << area2;
}
}
void handle_circle()
{
cout<<"\nWhat is the radius of the circle?";
cin>> R1;
area1 = PI*(R1 *R1);
if( R1 <=0)
{cout<<"\nRadius must be greater than 0, try again";
cin>> R1;
}
else
{
cout<< "\nThe area of a circle with a radius of " << R1 << " is" << area1;
}
}
您也可以使用 switch 语句，因为它比 if 语句更快
#include <iostream>
#include <iomanip>
using namespace std;
float area1, area2, area3, area4;
int R1;
int trib;
int trih;
int top;
int bott;
int traph;
int majxis;
int minxis;
const float PI= 3.14159;
void handle_circle();
void handle_ellipse();
void handle_triangle();
void handle_trapizoid();
int main()
{
int number;
cout<< "I'm starting my program ";
cout<<"\n1.Circle";
cout<<"\n2.triangle";
cout<<"\n3.trapezoid";
cout<<"\n4.ellipse ";
cout<<"\nEnter the corresponding number of your choice(1-4):";
cin>> number;
switch(number)
{
case 1:
handle_circle();
break;
case 2:
handle_triangle();
break;
case 3:
handle_ellipse();
break;
case 4:
handle_trapizoid();
break;
default:
{
cout<<"Integer is invalid, try again ";
}
}
}
void handle_trapizoid()
{
cout<<"\nWhat is the length of the top of the trapezoid? ";
cin>> top;
if(top <=0 )
{
cout<<"\n Invalid value for top length of trapezoid, try again";
}
else
{
cout<<"\nWhat is the length of the bottom of the trapezoid? ";
cin>> bott;
}
if (bott <= 0)
{
cout<<"Invalid value for bottom length of trapezoid, try again: ";
}
else
{
cout<<"What is the height of the trapezoid? ";
cin>>traph;
area3 = (top+bott)*0.5+traph;
}
if (traph <= 0)
{
cout<<"Invalid value for height of trapezoid";
}
else
{
cout<<"The area of a trapezoid with a bottom of " << bott << "and a top of " << top << "is " << area3;
}
}
void handle_ellipse()
{
cout<<"\nWhat is the length of the semi-major axis of the ellipse? ";
cin>> majxis;
if(majxis <=0)
{
cout<<"Invalid value for the semi-major axis, try again: ";
}
else
{
cout<<"What is the length for the semi-minor axis of the ellipse? ";
cin>> minxis;
area4= PI*minxis*majxis;
}
if(minxis <=0)
{
cout<<"Invalid value for the semi-minor axis, try again: ";
}
else
{
cout<<"The area of an ellipse with a semi-major axis of " << majxis<< "and a semi-minor axis of " << minxis << "is " << area4;
}
}
void handle_triangle()
{
cout<<"\nWhat is the length of the base of the triangle?";
cin>> trib;
if(trib<=0)
{
cout<<"\nInvalid Base of triangle, try again:";
}
else
{
cout<<"\nWhat is the height of the triangle? ";
cin>> trih;
area2 = (0.5*trib)*trih;
}
if(trih<=0)
{
cout<<"\nInvalid height of triangle, try again:";
}
else
{
cout<<"\nThe area of a trangle with a base of " << trib << "and a height of "<< trih <<" is " << area2;
}
}
void handle_circle()
{
cout<<"\nWhat is the radius of the circle?";
cin>> R1;
area1 = PI*(R1 *R1);
if( R1 <=0)
{cout<<"\nRadius must be greater than 0, try again";
cin>> R1;
}
else
{
cout<< "\nThe area of a circle with a radius of " << R1 << " is" << area1;
}
}