How can you find the number of duplicate characters in a string using Python?

1 year ago
Benjamin Taylor
2 minutes

You can use dictionaries in Python to find the number of duplicate characters in a string. Here are the specific steps:

  1. Create an empty dictionary to store characters and their occurrences.
  2. Iterate through each character in the string.
  3. If the character is not in the dictionary, it is added as a key with a value of 1.
  4. If the character is already in the dictionary, increment the corresponding value by 1.
  5. Finally, loop through the key-value pairs in the dictionary, and output the repeated characters along with their counts.

Here is an example of implementing the above steps using Python code:

def count_duplicate_chars(string):
    char_count = {}  # 创建一个空字典

    # 遍历字符串中的每个字符
    for char in string:
        # 如果字符不存在于字典中，则将字符作为键，值设为1，并添加到字典中
        if char not in char_count:
            char_count[char] = 1
        # 如果字符已经存在于字典中，则将对应的值加1
        else:
            char_count[char] += 1

    # 遍历字典中的键值对，输出重复字符及其个数
    for char, count in char_count.items():
        if count > 1:
            print(f"字符 '{char}' 重复了 {count} 次。")

# 测试示例
count_duplicate_chars("hello")  # 输出：字符 'l' 重复了 2 次。
count_duplicate_chars("Python")  # 输出：字符 'P' 重复了 2 次。
count_duplicate_chars("programming")  # 输出：字符 'r' 重复了 2 次。

In the above code, we used a dictionary called char_count to store the characters and their frequencies. We first iterate through each character in the string, then perform different operations based on whether the character exists in the dictionary or not. Finally, we iterate through the key-value pairs in the dictionary and output the repeated characters along with their frequencies.

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