Basic Data Types

  This section introduces data types in esProc and the functions for judging data types.

1.3.1 esProc data types

This section explains the data types esProc supports and the functions for judging data types. esProc provides the following basic data types:

Integer

32-bit integers between -2³¹ ~ 2³¹-1, that is, the value range is -2147483648~2147483647. The type conversion function int() is used to convert other types of data into a 32-bit integer.

Long integer

64-bit integers between -2⁶³~2⁶³-1; the value range is bigger than that of the integer type data. The type conversion function long() is used to convert other types of data into a long integer.

 

A long integer can be specially represented by appending a capital letter L to an integer. Compared with integers, long integers have a bigger value range. Strings starting with 0x can be used to represent the hexadecimal long integers:

	A
1	123456789
2	123456789L
3	12345678900
4	0x00FF

The value range of common integers is -2³¹~2³¹-1, that is, -2147483648~2147483647, so A1’s numeric value is an integer. A2 adds an L after the integer and will be identified as a long integer. In A3, the number 12345678900 is beyond the value range of common integers and will be parsed automatically into a long integer. It is a hexadecimal constant that cell A4 contains. Values of A1, A2, A3 and A4 are as follows:

    

In esProc, numeric values are displayed right-aligned. Integers are in blue and long integers are in black.

Floating-point number

64-bit floating-point numbers, the commonest data type esProc uses, are involved in almost all decimal-related computations. The type conversion function float() is used to convert other types of data to a floating-point number. Because floating-point numbers are stored in binary format, there could be errors in the computations.

	A
1	43.41
2	-4.45E13
3	3%
4	=float(54)

Values of A1, A2, A3 and A4 are as follows:

    

 The floating-point number in A2 is represented in scientific notation. A3 contains a floating-point number represented by a percentage, which can be only used in a constant cell, instead of in an expression. As shown above, floating-point numbers will be displayed in dark pink.

Big decimal

Big decimal is the most error-free way to store any decimal real number, yet it uses more memory and has a low computational efficiency. The type conversion function decimal() is used to convert other types of data (such as the string type data) into a big decimal.

	A
1	5.2
2	=A1*A1
3	=decimal("5.2")
4	=A3*A3

5.2 in A1 is a floating-point number; A3 converts the string “5.2” into a big decimal. The results in A2 and A4 are as follows:

 

 It can be seen that the calculation involving a binary-format floating-point number gets an inaccurate result, while the calculation using a big decimal has an accurate one. The result of computing a big decimal is also a big decimal. esProc displays big decimal in red.

Real number

The real number covers four data types: integer, long integer, floating-point number and big decimal. number() is the type conversion function for converting other types of data to a real number.

Boolean

This data type stores true or false value.

	A
1	true
2	false
3	=4>2
4	=13%3==0

Values of A1, A2, A3 and A4 are as follows:

    

String

When used in an expression, this type of data needs to be double quoted and uses the right slash \ as the escape character if needed. If the string data is defined as a constant directly, the double quotation marks are not needed. string() function is used to convert other types of data to strings. When concatenating two strings x and y using an expression, you can add a space between them, that is, x y; or just add them up like x+y. The latter requires that both x and y are strings.

Because if one of them is a real number, the result will be a real number, rather than a string. To concatenate a real number and a string as concatenating two strings, you can use x/y, whose result will be a string - as long as one of the operands is a string.

The esProc rule of escaping strings is the same as that of JAVA. For details, please refer to Escape Character.

	A
1	Amy
2	="State:\tTX"
3	="Texas"/"Dallas"
4	=A1+3.14
5	=A1/3.14

Values of A1, A2, A3, A4 and A5 are as follows:

  

 

Datetime

This type of data is written in the format of yyyy-mm-dd and hh:mm:ss. Type conversion functions - date(), time() and datetime() - are used to convert string data or long integer data to a date, time, or datetime.

	A
1	2014-10-5
2	22:15:30
3	=date("2014" "-10" "-5")

Values of A1, A2 and A3 are as follows:

   

Besides being able to convert strings into a date, the date function in A3 can generate a date value by setting the year, month and date, like date(2014,10,5), which produces a same result.

In esProc, boolean data, string data, and datetime data are displayed left-alligned and in black.

Click Tool -> Options on the menu to set the format of time/date data, the character code, and other options on the Environment tab.

Note: Precision may be sacrificed when a certain type of data is converted into another type of data.

Serial byte

A serial byte looks the same as an integer, but it is stored in a specified number of bytes. At present the maximum number of bytes a serial byte allowed to have is 16, which is 128 bits. The serial byte data is used as key values in a table. It is comparable but non-computable. Two serial byte values are compared byte to byte rather than as two numbers.

	A	B
1	=k(1111:2)
2	=A1.sbs(1)
3	=k(1111:4)
4	=[A3.sbs(1),A3.sbs(2),A3.sbs(3),A3.sbs(4)]	=k(0,0,4,87)
5	=A3==B4	=A3==A1
6	=k(111,0,0,4,0,0,0,87,0,87)	=k(133,255,0,128,0,0,0,0)
7	=A6<B6	=k(A6.sbs(5), A6.sbs(3:4):2, A6.sbs(8))

A1 uses k(n_i: l_i) function to generate a serial byte. The second parameter represents the specified integer’s length, that is, the number of bytes the integer occupies. Here we generate a two-byte serial byte value for integer 1111. Below is result of A1:

 

When viewed in a cell, a serial byte value will be displayed in hexadecimal notation bit by bit. In A1, 1111 takes up 2 bytes. Each byte is displayed as two hexadecimal numbers. So, integer 1111 is represented by the hexadecimal 0457.

Use k.sbs(n) function to get a certain byte of a serial byte value to generate an integer. A2 gets the integer generated from A1’s first byte. The hexadecimal number the first byte corresponds to is 04, and we convert it to a decimal number, as shown below:

 

A3 generates a serial byte of 4 bytes using integer 1111. A4 looks up the value of each byte in A3’s serial byte. We can also generate a serial byte by specifying values for bytes through k(ni,…) function. In this case when parameter l_i is absent, the integer values correspond to the bytes one by one. Below are results of A3, A4, and B4:

 

 

Let’s compare results of A3 and A1. As A3 specifies 4 bytes for 1111, the hexadecimal displayed is an 8-digit 00000457. The hexadecimal number for the 4th byte is 57, which corresponds to 87 when converted to a decimal. That’s just what A4 gets. B4 specifies the serial byte value byte one byte and gets same result as A3.

A5 and B5 compare A3’s serial byte value with those in B4 and A1 respectively. A3 and B4 are equal. However, two serial bytes values made up of different number of bytes are not equal even if they look the same. Below are results of A5 and B5:

 

To generate a serial byte through k(ni,…) function, each byte value should be an integer (≥0 &≤255) and consists of 16 bytes at most. According to value range for each single byte, only settings within 0~255 is correct. If beyond the range, only n_i data specified for the last byte is valid. Below are results of A6 and B6:

 

B6’s serial byte data is greater than A6’s because the comparison is performed byte by byte. Every serial byte data has 16 bytes, and they are compared byte by byte. The comparison is irrelevant to the number of bytes specified in serial byte definition. In this example, A6 defines ten bytes while A7 defines eight, but they can still be compared. Below is A7’s result:

Besides k(n,…) that gets a specified byte from serial byte value k to generate a new serial byte value, we have k(n:l,…) to specify one or more bytes to generate a new serial byte value. Below is result of B7:

B7’s expression and B4’s expression k(0,0,4,87) have same effect, but the former specifies the middle two bytes at a time and gets bytes from A6’s serial byte value.

1.3.2 Data type determination

esProc offers the following functions to determine the data type:

ifnumber(x) 

Check if x is a real number

ifstring(x)

Check if x is a string value

ifdate(x)

Check whether x is a date or a datetime value

iftime(x)

Check if x is a time value

	A
1	=ifnumber(3.5)
2	=ifstring(now())

In A1, the floating-point number 3.5 is a real number. now() function in A2 computes the current date and time and the result is not a string. The results in A1 and A2 are as follows: