C ++简单IO元音计数程序

Question

char ch;
//Get data from user 
cout << "Enter your sentence on one line followed by a # to end it: " << endl;

while (cin >> character && character != '#') 
{
    cin.get(ch); 
    ch = static_cast<char>(toupper(ch));
    outFile << ch;

    if (character == 'A' || character == 'E' || character == 'I' || character == 'O'
                || character == 'U')
    {
        vowelCount ++;

    }
}
outFile << "number of vowels: " << vowelCount << endl;

I am trying to input a sentence, read how many vowels, blank spaces, and other characters it has. But the vowelCount is never right and I can't get it to write the same sentence to output file either. Any hints?

Answer 1

You have not shown the declaration / initialization of the variable vowelCount . I assume you have only declared (and not initialized) it using a statement like:

int vowelCount; // notice the variable is not initialized.

In C++, int variables have no default value. If you have written such code, you can correct it by explicitly initializing its value with a statement like:

int vowelCount = 0;

Moreover, your loops reads 2 characters at each iteration (skipping one out of two characters) and you are missing the vowel Y .

The corrected example would look like:

//Get data from user 
cout << "Enter your sentence on one line followed by a # to end it: " << endl;

int vowelCount = 0;
while (cin >> character && character != '#') 
{
    character = toupper(character);

    if (character == 'A' || character == 'E' || character == 'I' || character == 'O'
                || character == 'U' || character == 'Y')
    {
        vowelCount ++;

    }
}
outFile << "number of vowels: " << vowelCount << endl;

Answer 2

Just like pmr's comment indicates, the problem is that you are reading in two characters with each loop iteration, but only checking the first one. Both of these statements consume a character from stdin:

cin >> character
...
cin.get(ch)

all you need to do is this:

while (cin >> character && character != '#') 
{
    character = static_cast<char>(toupper(character));