5.10.cpp

#include <iostream>
#include <cctype>	// tolower

using std::cout;
using std::cin;
using std::endl;

int main() {
	unsigned aCnt = 0, eCnt = 0, iCnt = 0, oCnt = 0, uCnt = 0;
	char ch;
	while (cin >> ch) {
		switch (tolower(ch)) {	//	or you could use ch but make two cases for each upper or lower vowel
			case 'a':
				++aCnt;
				break;
			case 'e':
				++eCnt;
				break;
			case 'i':
				++iCnt;
				break;
			case 'o':
				++oCnt;
				break;
			case 'u':
				++uCnt;
				break;
			default:
				break;
		}
	}
	cout << "Number of vowel a: \t" << aCnt << '\n'
		 << "Number of vowel e: \t" << eCnt << '\n'
		 << "Number of vowel i: \t" << iCnt << '\n'
		 << "Number of vowel o: \t" << oCnt << '\n'
		 << "Number of vowel u: \t" << uCnt << endl;
	return 0;
}