PowerScript Reference
PowerScript Functions

Description

Obtains a specified number of characters from a specified position in a string.

Syntax

Mid ( string, start {, length } )

Return value

String.

Returns characters specified in length of string starting at character start. If start is greater than the number of characters in string, the Mid function returns the empty string (""). If length is greater than the number of characters remaining after the start character, Mid returns the remaining characters. The return string is not filled with spaces to make it the specified length. If any argument's value is null, Mid returns null.

Usage

To search a string for the position of the substring that you want to extract, use the Pos function. Use the return value for the start argument of Mid. To extract a specified number of characters from the beginning or end of a string, use the Left or the Right function.

Examples

This statement returns RUTH:

Mid("BABE RUTH", 5, 5)

This statement returns "":

Mid("BABE RUTH", 40, 5)

This statement returns BE RUTH:

Mid("BABE RUTH", 3)

These statements store the characters in the SingleLineEdit sle_address from the 40th character to the end in ls_address_extra:

string ls_address_extra
ls_address_extra = Mid(sle_address.Text, 40)

The following user-defined function, called str_to_int_array, converts a string into an array of integers. Each integer in the array will contain two characters (one characters as the high byte (ASCII value * 256) and the second character as the low byte). The function arguments are str, a string passed by value, and iarr, an integer array passed by reference. The length of the array is initialized before the function is called. If the integer array is longer than the string, the script stores spaces. If the string is longer, the script ignores the extra characters.

To call the function, use code like the following:

int rtn
iarr[20]=0 // Initialize the array, if necessary
rtn = str_to_int_array("This is a test.", iarr)

The str_to_int_array function is:

long stringlen, arraylen, i
string char1, char2
 
// Get the string and array lengths
arraylen = UpperBound(iarr)
stringlen = Len(str)
 
// Loop through the array
FOR i = 1 to arraylen
    IF (i*2 <= stringlen) THEN
      // Get two chars from str
      char1 = Mid(str, i*2, 1)
      char2 = Mid(str, i*2 - 1, 1)
    ELSEIF (i*2 - 1 <= stringlen) THEN
      // Get the last char
      char1 = " "
      char2 = Mid(str, i*2 - 1, 1)
    ELSE
      // Use spaces if beyond the end of str
      char1 = " "
      char2 = " "
    END IF
    iarr[i] = Asc(char1) * 256 + Asc(char2)
NEXT
RETURN 1

For sample code that converts the integer array back to a string, see Asc.

See also

AscA

Left

Pos

Right

UpperBound

Mid method for DataWindows in the section called “Mid” in DataWindow Reference.