C++ ERROR redefinition of ‘class ***’

The error is as follows:
BaseSmoothingAlgorithm. H: 4:7: error: redefinition of “class BaseSmoothingAlgorithm ‘
BaseSmoothingAlgorithm. H: 4:7: error: the previous definition of ‘class BaseSmoothingAlgorithm’
Troubleshooting steps:
1. Find whether there are fewer classes “; “after the definition of the class. ; Find one after another, not this type of error
2. There are no macros to prevent them from being included more than once
#ifndef _BASESMOOTHINGALGORITHM_H_
#define _BASESMOOTHINGALGORITHM_H_
#include “BaseSmoothingAlgorithm.h”
#endif
To solve


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