C++嵌套循环没有提供任何值

Question

因此，这个嵌套循环应该为用户输入的每个学生生成10个练习的随机分数。在生成分数后，它必须将所有分数相加，并找到平均分数。然而，当我运行这个程序时，它没有给我任何值。代码如下：

int progExAvg, progExScore, studentAmt;
int counter = 0;
int progExTotal = 0;

srand(time(0));

cout << "Please enter how many students do you have in your class: ";
cin >> studentAmt;
cin.sync();

while (counter < studentAmt)
{
    for(int i = 0; i < 10; i++)
    {
        progExScore = rand() % 100 + 1;
        progExTotal = progExTotal + progExScore;
    }

    progExAvg = progExTotal / 10;



}
cout << progExAvg << endl;
return 0;

Answer 1

您从不递增counter，因此它总是小于studentAmt

while (counter < studentAmt)
{
    for(int i = 0; i < 10; i++)
    {
        progExScore = rand() % 100 + 1;
        progExTotal = progExTotal + progExScore;
    }

    progExAvg = progExTotal / 10;

    counter++;

}

Answer 2

移动这些声明

int progExTotal = 0;
int progExTotal = 0;

这句话

cout << progExAvg << endl;

while循环内部

以及这份声明

int progExScore;

在for循环中

考虑到使用像10这样的魔术数字不是一个好主意，最好使用有意义的名字。

此外，您还必须增加可变计数器。例如

const int TOTAL_EXERCISES =  10;

while (counter++ < studentAmt)
{
    int progExTotal = 0;
    int progExTotal = 0;

    for(int i = 0; i < TOTAL_EXERCISES; i++)
    {
        int progExScore = rand() % 100 + 1;
        progExTotal = progExTotal + progExScore;
    }

    progExAvg = progExTotal / TOTAL_EXERCISES;

    cout << progExAvg << endl;
}