CODEWITHSUNDEEP
phpvalidationdatelaravel-5.3strtotime
Sergio Donati
Sergio Donati

Reputation: 101

(PHP) strtotime function false positive with char

I don't understand why this is a valid date

strtotime("1920-09k-12") // -1556877600 // I expect false

I see that adding a char after the month or day is a valid date.

strtotime("1920-09-12d") // -1555905600 // I expect false
strtotime("1920-09n-12") // -1556838000 // I expect false

Instead

strtotime("1920-09k-12k") // false
strtotime("1920r-09-12") // false
strtotime("1920-09-12") // -1555862400

Is this the expected behaviour?

I use Laravel and the strtotime function is used for validate date in the framework but when go to save a record in DB with a "false positive" date a QueryException is raised. I resolved the problem with a custom validation but i'm curious to know why strtotime has this behaviour.

Upvotes: 1

Views: 154

Answers (1)

Francis Eytan Dortort
Francis Eytan Dortort

Reputation: 1447

This may not fully answer your question, but examining the results of date_parse() for your sample dates, it appears that the first letter in the string is interpreted as the timezone, and the remainder of the string as well, which either causes a warning or an error of "Double timezone specification", and in the case of an error, the DateTime cannot be created.

For example:

date_parse("1920-09-12d")

Array
(
    [year] => 1920
    [month] => 9
    [day] => 12
    [hour] => 
    [minute] => 
    [second] => 
    [fraction] => 
    [warning_count] => 0
    [warnings] => Array
        (
        )

    [error_count] => 0
    [errors] => Array
        (
        )

    [is_localtime] => 1
    [zone_type] => 2
    [zone] => -240
    [is_dst] => 
    [tz_abbr] => D
)

Notice the timezone "D"

date_parse("1920-09n-12")

Array
(
    [year] => 1920
    [month] => 9
    [day] => 1
    [hour] => 
    [minute] => 
    [second] => 
    [fraction] => 
    [warning_count] => 1
    [warnings] => Array
        (
            [8] => Double timezone specification
        )

    [error_count] => 0
    [errors] => Array
        (
        )

    [is_localtime] => 1
    [zone_type] => 2
    [zone] => 60
    [is_dst] => 
    [tz_abbr] => N
)

Notice the timezone "N", furthermore the 12 is not interpreted as the day of month, but rather I suspect "-12" is interpreted as an additional timezone specification, hence the warning.

date_parse("1920r-09-12")

Array
(
    [year] => 
    [month] => 
    [day] => 
    [hour] => 19
    [minute] => 20
    [second] => 0
    [fraction] => 
    [warning_count] => 1
    [warnings] => Array
        (
            [5] => Double timezone specification
        )

    [error_count] => 1
    [errors] => Array
        (
            [8] => Double timezone specification
        )

    [is_localtime] => 1
    [zone_type] => 2
    [zone] => 300
    [is_dst] => 
    [tz_abbr] => R
)

Notice the timezone "R", furthermore no date is parsed, rather 1920 is interpreted as the time 19:20:00, and I suspect the remainder of the string is interpreted as 2 timezones, "-09" & "-12", causing the error "Double timezone specification".

Upvotes: 1

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