在字符串中查找子字符串并在 Python 中返回子字符串的索引

def find_str(s, char):
    index = 0
    if char in s:
        c = char[0]
        for ch in s:
            if ch == c:
                if s[index:index + len(char)] == char:
                    return index
            index += 1
    return -1
print(find_str("India Canada Japan", "Canada"))
print(find_str("India Canada Japan", "cana"))
print(find_str("India Canada Japan", "Uae"))

Output:

6
-1
-1