What’s the difference between is_null($var) and ($var === null)?

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empty() and isset() do not trigger a PHP warning if their parameter is an undefined variable.
In most cases, such a warning is desirable to pinpoint the bugs. So only use the functions if you believe your variable can be legitimately undefined. It normally happens with an array index.

✅ is true

❌ is false

        |  isset   | is_null | === null | == null | empty   |
|-------|----------|---------|----------|---------|---------|
| unset |    ❌   |    ✅   |    ✅    |    ✅  |    ✅   |
|  null |    ❌   |    ✅   |    ✅    |    ✅  |    ✅   |
|  true |    ✅   |    ❌   |    ❌    |    ❌  |    ❌   |
| false |    ✅   |    ❌   |    ❌    |    ✅  |    ✅   |
|     0 |    ✅   |    ❌   |    ❌    |    ✅  |    ✅   |
|     1 |    ✅   |    ❌   |    ❌    |    ❌  |    ❌   |
|    \0 |    ✅   |    ❌   |    ❌    |    ❌  |    ❌   |
|    "" |    ✅   |    ❌   |    ❌    |    ✅  |    ✅   |
|    [] |    ✅   |    ❌   |    ❌    |    ✅  |    ✅   |

Summary:🔸♦️🔸

  • empty is equivalent to == null
  • is_null is equivalent to === null
  • isset is inverse of is_null and === null

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