iec10967

Long integer is transformed when inserted in shorter column, not truncated. Why? What is the formula?

由 最后都变了- 提交于 2019-11-27 02:12:25
I have a column of type integer with length 10: `some_number` int(10) unsigned NOT NULL Into this column I insert a number that is too long: $some_number = 715988985123857; $query = "INSERT INTO this_table SET some_number = ?"; $stmt = $mysqli->prepare($query); $stmt->bind_param('i', $some_number); $stmt->execute(); When I look at what is in the table, the number is now: 2147483647 How and why did 715988985123857 turn into 2147483647 ? Why didn't it get truncated? What is the mechanism behind this transformation, and can the resulting number be calculated with some formula? I'm not looking for

Long integer is transformed when inserted in shorter column, not truncated. Why? What is the formula?

由 ＊爱你＆永不变心＊ 提交于 2019-11-26 10:01:04
问题 I have a column of type integer with length 10: `some_number` int(10) unsigned NOT NULL Into this column I insert a number that is too long: $some_number = 715988985123857; $query = \"INSERT INTO this_table SET some_number = ?\"; $stmt = $mysqli->prepare($query); $stmt->bind_param(\'i\', $some_number); $stmt->execute(); When I look at what is in the table, the number is now: 2147483647 How and why did 715988985123857 turn into 2147483647 ? Why didn\'t it get truncated? What is the mechanism

How to count the number of set bits in a 32-bit integer?

由 半腔热情 提交于 2019-11-25 22:52:58
问题 8 bits representing the number 7 look like this: 00000111 Three bits are set. What are algorithms to determine the number of set bits in a 32-bit integer? 回答1: This is known as the 'Hamming Weight', 'popcount' or 'sideways addition'. The 'best' algorithm really depends on which CPU you are on and what your usage pattern is. Some CPUs have a single built-in instruction to do it and others have parallel instructions which act on bit vectors. The parallel instructions (like x86's popcnt , on

What is the rationale for all comparisons returning false for IEEE754 NaN values?

由 亡梦爱人 提交于 2019-11-25 22:18:18
问题 Why do comparisons of NaN values behave differently from all other values? That is, all comparisons with the operators ==, <=, >=, <, > where one or both values is NaN returns false, contrary to the behaviour of all other values. I suppose this simplifies numerical computations in some way, but I couldn\'t find an explicitly stated reason, not even in the Lecture Notes on the Status of IEEE 754 by Kahan which discusses other design decisions in detail. This deviant behavior is causing trouble
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