PHP: Why do we need string comparison function?

问题:

The comparision operators < <= > >= can be applied for strings as well. So why do we need special function for string comparision: strcmp ?

回答1:

Because there are several variations:

Depending on the function, the answer to these questions vary:

• Is it case sensitive? (strcmp vs strcasecmp, strnatcmp vs strnatcasecmp)
• Depends it depend on the locale? (strcoll does)
• Can I specify a collation? (strcoll is affected by setlocale)

Additionaly, the comparison operators also give true or false. strcmp gives an integer so it can encode simultaneously whether there's identity (return 0) or, if it not, which is is bigger (depending on whether the value is positive or negative).

回答2:

Although there are no overloads in PHP for strcmp, strcmp results in 3 different values -1 for less than, 0 for equals and +1 for greater than the compared string. With < = <= > >= you will have (sometimes) to do multiple checks one after another.

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