Description:
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The semantics of relational operators (in 10-expressions.md) is different with the actual behavior of PHP, in case that both operands are string (the semantics says rules 2 and 4 are applied).

In this case, numeric comparison is applied only if both operands are numeric string without overflow, otherwise lexical comparison is applied.

Some examples are shown below.
echo ('1' == '0x1') . "\n"; // true
echo ('1' == '1a') . "\n"; // false
echo ('1234567890' == '1234567890.0') . "\n"; // true
echo ('123456789012345678901234567890' == '123456789012345678901234567890.0') . "\n"; // false
echo ('1e10' == '1.0e10') . "\n"; // true
echo ('1e1000' == '1.0e1000') . "\n"; // false