------
## 最终结论
```python
def char_frequency(string):
    frequency = {}
    for char in string:
        if char in frequency:
            frequency[char] += 1
        else:
            frequency[char] = 1
    return frequency

# Test cases
assert char_frequency('python') == {'p': 1, 'y': 1, 't': 1, 'h': 1, 'o': 1, 'n': 1}
assert char_frequency('program') == {'p': 1, 'r': 2, 'o': 1, 'g': 1, 'a': 1, 'm': 1}
assert char_frequency('language') == {'l': 1, 'a': 2, 'n': 1, 'g': 2, 'u': 1, 'e': 1}
```