matchChar.py

def nCommonChars(str1, str2):
    temp1 = str.lower()
    temp2 = str.lower()

    count = 0
    for i in range(len(temp1)):
        ch1 = temp1[i]
        if not (ch1 in temp1[:i]):
            for ch2 in temp2:
                if ch1 == ch2:
                    count +=1
                    break
    return count