------
## 最终结论
```python
def remove_splchar(input_string):
    result = ''
    for char in input_string:
        if char.isalnum():
            result += char
    return result

# Test cases
assert remove_splchar('python  @#&^%$*program123') == 'pythonprogram123'
assert remove_splchar('python %^$@!^&*()  programming24%$^^()    language') == 'pythonprogramming24language'
assert remove_splchar('python   ^%&^()(+_)(_^&67)                  program') == 'python67program'
```