Question

我一直在尝试为课程编写程序，但出于某种原因，当我输入程序的第一个时，它转到案例1但是它不允许我输入字符串并直接返回到菜单。例）输入1结果是：输入字符串：01。添加数字但忽略任何不是数字的数字。如果我使用常规cin语句，代码将执行完全正常。我不明白为什么这样做。有人可以帮忙吗？

#include <iostream>
#include <cctype>

using namespace std;

void firstChoice(char []);

int main()
{
    int choice;
    int answer;
    const int SIZE = 100;
    char line[SIZE];


do
{
    cout << "1. Adds numbers but ignores anything thats not a number." << endl;
    cout << "2. Count the number of consonants in a string." << endl;
    cout << "3. Counts the vowels in a string." << endl;
    cout << "4. Counts whitespace characters in a string." << endl;
    cout << "Enter a number to access that program or 0 to end it: ";
    cin >> choice;

    switch(choice)
    {
        case 1:
            cout << "\nEnter a string: ";
            cin.getline(line, SIZE);
            firstChoice(line);
            break;

        case 2:
            cout << "Enter a string: ";
            cin.getline(line, SIZE);
            break;

        case 3:
            cout << "Enter a string: ";
            cin.getline(line, SIZE);
            break;

        case 4:
            cout << "Enter a string: ";
            cin.getline(line, SIZE);
            break;
    }
}
while(choice != 0);
return 0;
}

void firstChoice(char line[])
{
int size2 = 0;
int sum = 0;

while(line[size2] != '\0')
{
    if(isalpha(line[size2]))
    {
        line[size2] = 0;
    }
    sum += line[size2];

    size2++;
}
cout << sum;
}

Answer 1

在此声明之后

cin >> choice;

使用

#include <limits>

//...

cin >> choice;
std::cin.ignore( std::numeric_limits<std::streamsize>::max(), '\n' );

cin.getline（）不使用switch语句

1 个答案: