public class PracticeWithLoops {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		System.out.println(countChar('a', "Today is Tuesday"));
		System.out.println(makeUppercase('a', "a cat"));
		System.out.println(firstLetters("one  two     three"));
	}

	/**
	 * Returns the number of times the given character appears in the given
	 * string
	 * 
	 * @param c
	 *            the character to find
	 * @param s
	 *            the string to check
	 */
	public static int countChar(char c, String s) {
		int count = 0;
		for (int i = 0; i < s.length(); i++) {
			if (s.charAt(i) == c) {
				count++;
			}
		}
		return count;
	}

	/**
	 * Returns the string that is s where all of the occurrences of c are
	 * replaced with c uppercase (e.g. if s is "a cat" and c is 'a', the method
	 * returns "A cAt")
	 * 
	 * @param c
	 *            the character to make uppercase
	 * @param s
	 *            the string to process
	 */
	public static String makeUppercase(char c, String s) {
		String s2 = "";
		for (int i = 0; i < s.length(); i++) {
			char letter = s.charAt(i);
			if (letter != c) {
				s2 += letter;
			} else {
				s2 += Character.toUpperCase(c);
			}
		}
		return s2;
	}

	/**
	 * Returns a string that contains the first letter of each word of the given
	 * string
	 * 
	 * @param s
	 *            the string to process
	 */
	public static String firstLetters(String s) {
		String first = "";
		for (int i = 0; i < s.length(); i++) {
			char c = s.charAt(i);
			// take it only if c is a letter
			if (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z') {
				// and c is preceded by a space or is at index 0
				if (i == 0 || s.charAt(i - 1) == ' ') {
					first += c;
				}
			}
		}
		return first;
	}

}