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Storing sex (gender) in database
...,147,483,648 to 2,147,483,647
BIT 1 (2 if 9+ columns) 2 (0 and 1)
CHAR(1) 1 26 if case insensitive, 52 otherwise
The BIT data type can be ruled out because it only supports two possible genders which is inadequate. While INT supports more than two options, it takes...
#pragma pack effect
...example, given 4-byte integers and the following struct:
struct Test
{
char AA;
int BB;
char CC;
};
The compiler could choose to lay the struct out in memory like this:
| 1 | 2 | 3 | 4 |
| AA(1) | pad.................. |
| BB(1) | BB(2) | BB(3) | BB(4) |
| CC(1) | pa...
Calling constructors in c++ without new
...new object on the stack by calling a constructor of the format Thing(const char*).
The second one is a bit more complex. It essentially does the following
Create an object of type Thing using the constructor Thing(const char*)
Create an object of type Thing using the constructor Thing(const Th...
best practice to generate random token for forgot password
...es DATETIME,
PRIMARY KEY(id)
);
... you need to add one more column, selector, like so:
CREATE TABLE account_recovery (
id INTEGER(11) UNSIGNED NOT NULL AUTO_INCREMENT
userid INTEGER(11) UNSIGNED NOT NULL,
selector CHAR(16),
token CHAR(64),
expires DATETIME,
PRIMARY K...
C/C++中的段错误（Segmentation fault） - C/C++ - 清泛网 - 专注C/C++及内核技术
...ce
例子2：
Code:
#include <stdio.h>
int main(){
char *p;
p = NULL;
*p = 'x';
printf("%c", *p);
return 0;
}
很容易发现，这个例子也是试图往内存地址0处写东西。
这里我们通过gdb来查看段错误所在的行
...
Best practices/performance: mixing StringBuilder.append with String.concat
...end(sN).toString();
concat()
String s = s1.concat(s2);
String creates char[] array that can fit both s1 and s2. Copies s1 and s2 contents to this new array. Actually requires less work then + operator.
StringBuilder.append()
Maintains an internal char[] array that grows when needed. No extra ...
Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C
... Bit Twiddling Hacks page:
Fastest (lookup table):
static const unsigned char BitReverseTable256[] =
{
0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,
0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF...
Converting string to byte array in C#
...[] GetBytes(string str)
{
byte[] bytes = new byte[str.Length * sizeof(char)];
System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
return bytes;
}
static string GetString(byte[] bytes)
{
char[] chars = new char[bytes.Length / sizeof(char)];
System.Buffer.B...
Explain the use of a bit vector for determining if all characters are unique
...
@Ivan Man, I was thinking the same thing. Even the selected answer didn't explain about the operators. Thank you for the detailed info.
– WowBow
Jan 6 '15 at 20:11
...
How to create CSV Excel file C#? [closed]
...Object = obj;
var line = String.Join(delimeter, propertyInfos.Select(x => SanitizeValuesForCSV(x.GetValue(localObject, null), delimeter)));
sb.AppendLine(line);
}
return sb.ToString();
}
private static string SanitizeValuesForCSV(object value, s...