When should I use 'class' vs. 'typename' in template parameters?

Understanding 'class' and 'typename' in Template Parameters

In C , both 'class' and 'typename' can be used to specify template parameters. While they may seem interchangeable, historical context offers insights into their usage preference.

Historical Background

When first introducing templates, Bjarne Stroustrup opted for 'class' to specify template types, considering 'typename' as an unnecessary keyword. However, concerns arose regarding potential confusion due to 'class' having multiple meanings.

The Introduction of 'typename'

To address this ambiguity, the C committee decided to create a new keyword specifically meant for specifying template types: 'typename.' This was aimed at enhancing syntactic clarity and reducing the risk of misinterpretation.

Current Usage Considerations

Today, both 'class' and 'typename' remain valid choices for defining template parameters. There is no inherent technical difference between their usage. Personal preference or specific coding styles may influence a developer's choice between the two.

Note: Prior to C 17, for "template template" parameters, 'class' was mandatory. However, in modern C , 'typename' is universally acceptable.

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