谁能弄清楚为什么我的循环会失败?

循环的主要问题是您将valid设置为true但永远不会设置为false，因此语句while (!valid)永远不会计算为 false。

另一个一般性评论是代码的布局有太多的嵌套循环。这可以简化很多。

我没有测试下面的代码，但这种类型的结构更容易阅读 - 即分别进行每个输入，而不是将所有输入混在一起！ ：-(

//Ask user for cubeLength and validate input for integer values
valid = true;
do {
cout << "Please enter a numerical value for the length of a cube" <<endl;
cin >> cubeLength;
if (!cin.good()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, 'n');
cout << "Invalid cube length. Input is not an integer" << endl;
}     
} while (!valid);
//Ask user for cubeWidth and validate input for integer values
do {
cout << "Please enter a numerical value for the width of a cube" <<endl;
cin >> cubeWidth;
if (!cin.good()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, 'n');
cout << "Invalid cube width. Please try again" << endl;
}    
} while (!valid);

//Ask user for cubeHeight and validate input for integer values
do {
cout << "Please enter a numerical value for the width of a cube" <<endl;
cin >> cubeWidth;
if (!cin.good()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, 'n');
cout << "Invalid cube height. Please try again" << endl;
} 
}while (!valid);

第一次设置valid = true后，它会一直保持true直到最后。在再次测试之前，您应该将其带回false。

感谢所有提供帮助和反馈的人：

这个问题现在对我来说非常明显，那就是在输入验证失败后，布尔值在循环开始时没有重置。

我根据建议重做了整个代码，现在有一个稳定的程序！:)

#include <iostream>
using namespace std;
//Global Variables
int cubeLength = 0;
int cubeWidth = 0;
int cubeHeight = 0;
int cubeSurfaceArea = 0;
int cubeVolume = 0;
bool valid = true;
char choice;
int main() {
do {
//Ask user for cubeLength and validate input for integer values
do {
valid = true;
cout << "Please enter a numerical value for the length of a cube" <<endl;
cin >> cubeLength;
if (cin.fail()) {
valid = false;
cin.clear();
cin.ignore(INT_MAX, 'n');
cout << "Invalid cube length. Input is not an integer" << endl;
}
} while (!valid);
//Ask user for cubeWidth and validate input for integer values
do {    
valid = true;
cout << "Please enter a numerical value for the width of a cube" <<endl;
cin >> cubeWidth;
if (cin.fail()) {
valid = false;  
cin.clear();
cin.ignore(INT_MAX, 'n');
cout << "Invalid cube width. Input is not an integer" << endl;
}
} while (!valid);
//Ask user for cubeHeight and validate input for integer values
do {
valid = true;
cout << "Please enter a numerical value for the height of a cube" <<endl;
cin >> cubeHeight;
if (cin.fail()) {   
valid = false;
cin.clear();
cin.ignore(INT_MAX, 'n');
cout << "Invalid cube height. Input is not an integer" << endl;
}
}while (!valid);
//Perform calculations for surface area and volume then assign them to their associated variables
if (cubeLength >= 1 && cubeWidth >= 1 && cubeHeight >= 1)
{
cubeSurfaceArea = ((2*(cubeWidth*cubeLength))+(2*(cubeLength*cubeHeight))+(2*(cubeWidth*cubeHeight)));
cubeVolume = (cubeWidth*cubeLength*cubeHeight);
}
else {
cout << "Sorry, one or more cube inputs is invalid. Ending program. Please restart and try again." << endl;
return 0;
}   
//Output surface area and volume to user
cout << "Length = " << cubeLength << " Width = " << cubeWidth << " Height = " << cubeHeight << endl;
cout << "The surface area of your cube is " << cubeSurfaceArea << "." << endl;
cout << "The volume of your cube is " << cubeVolume << "." << endl;
cout << "Would you like to try again? (y/n)" << endl;
cin >> choice;
} while (choice != 'n');
//Pause system and end program
return 0;
}