Strpos function, what to do with it

Strpos function

  /> Recommended [C]
    
  Special recommendation of/> [a]
    
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  /> Special recommendation [O]
    
  Special recommendation of/> [n]

I want to judge if $row[' flag ' is c,a,h,o,n one of them. Add a pair of hooks. Why is it that you can only judge the recommended "C"? The back is not showing. Since the first one can succeed, it should be right.
------Solution--------------------
Strpos ($row [' flag '], ' C ')!== false
------Solution--------------------
if (Strpos ($row [' flag '], ' C ')!== false)
Other similar

Strpos returns an integer (no return logical leave found)
' true ' is converted to 0 in a numeric comparison
If the first character of the $row [' flag '] is C, it happens to be matched
The other characters returned are not 0, so the match will not succeed

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