Difference between revisions of "String Manipulation Functions"

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:''See [[Calculation Icon Properties]]''
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__TOC__
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==String Functions==
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The String functions are a set of string manipulation functions that can be used to edit, change and examine the strings.
 
The String functions are a set of string manipulation functions that can be used to edit, change and examine the strings.
  
 
To add a function, drag it into the calculation box. The user can then edit this base code with the variables required.
 
To add a function, drag it into the calculation box. The user can then edit this base code with the variables required.
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{| style="margin:auto; text-align:center;"
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|-
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|[[File:Btn_Calculation.gif|border]]
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| width="50px" |→
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|[[File:Gen_Calculation_Flowchart_Icon_01.png]]
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|width="50px" |→
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|[[File:Gen_StringFunctions_01.jpg]]
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|}
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Example Strings used in explaining the functions below:
 
Example Strings used in explaining the functions below:
  
−
Str1[20] = "Hello "
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Str1[20]
  
−
Str2[10] = "World"
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Str2[20]
  
−
TestStr[20]
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TestStr[40]
  
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===Assigning Strings===
  
 
=
 
=
  
−
Changes the string to the string given. If the array.
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To assign a string value to a string variable you can simply use the = character.
  
−
If the string is longer than the array size then any extra characters are lost.
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Str1 = "Hello "
  
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Str2 = "World"
  
−
TestStr = Str1 + Str2
 
  
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Strings can also be treated like byte arrays to allow you to manipulate the individual bytes. For string data to work correctly with other string functions the end of the data must be signified with a 0 or null byte.
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Str1[0] = 'H'
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Str1[1] = 'e'
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Str1[2] = 'l'
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Str1[3] = 'l'
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Str1[4] = 'o'
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Str1[5] = ' '
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Str1[6] = 0
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Assigning a string constant to a string variable will automatically add the null byte to the end of the string for you.
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Str1 = "Hello "
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Strings can also be used with escape characters such as \n (newline), \r (carriage return), \t (tab), \xXX (hexadecimal byte value), \\ single backslash character.
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Str1 = "Hello\n\rWorld"
  
−
TestStr is now "Hello World"
 
  
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===Concatenating Strings===
  
 
+  
 
+  
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If the resulting string is longer than the array size of the receiving string then any extra characters are lost.
 
If the resulting string is longer than the array size of the receiving string then any extra characters are lost.
  
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Str1 = "Hello "
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 +
Str2 = "World"
  
 
TestStr = Str1 + Str2  
 
TestStr = Str1 + Str2  
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TestStr is now "Hello World"
 
TestStr is now "Hello World"
  
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 +
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Multiple concatenations are best done like this to avoid using excess memory. Note that each line contains only two values to be added together.
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TestStr = "Multiple " + Str1
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TestStr = TestStr + Str2
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TestStr is now "Multiple Hello World"
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'''NOTE:''' Due to a limitation in generated code the result of multiple concatenations in one operation is limited to 20 characters. So the result of Str1 + Str2 + Str3 should not exceed 20 characters.
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===Converting a numeric value/variable to a string===
  
 
'''ToString$(value)'''  
 
'''ToString$(value)'''  
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TestStr = ToStr$(1234)  
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TestStr = ToString$(1234)  
  
  
 
TestStr is now "1234"
 
TestStr is now "1234"
  
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===Converting a string to upper case===
  
 
'''ToUpper$(string)'''  
 
'''ToUpper$(string)'''  
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TestStr is now "HELLO "
 
TestStr is now "HELLO "
  
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===Converting a string to lower case===
  
 
'''ToLower$(string)'''  
 
'''ToLower$(string)'''  
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TestStr is now "hello "
 
TestStr is now "hello "
  
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===Finding the length of a string===
  
 
'''Length$(string)'''  
 
'''Length$(string)'''  
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Note: Str1 array size is 20, but has a String of only 6 characters currently assigned to it hence the return value of 6.
 
Note: Str1 array size is 20, but has a String of only 6 characters currently assigned to it hence the return value of 6.
  
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===Getting a single character from a string===
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'''Char$(string, number)'''
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Retrieves a single byte from the specified position in the string.
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Str1= "hello"
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RetVal = Char$(Str1, 0)
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Retval is now 'H'.
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RetVal = Char$(Str1, 4)
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Retval is now 'o'.
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RetVal = Char$(Str1, 5)
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Retval is now 0 (NULL terminator to mark the end of valid data).
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String bytes can also be accessed directly using standard C square bracket array notation.
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RetVal = Str1[4]
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Retval is now 'o'.
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===String subset - characters from the start of the string===
  
 
'''Left$(string, size)'''  
 
'''Left$(string, size)'''  
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TestStr is now "Hel"
 
TestStr is now "Hel"
  
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===String subset - characters from the end of the string===
  
 
'''Right$(string, size)'''  
 
'''Right$(string, size)'''  
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TestStr is now "lo "
 
TestStr is now "lo "
  
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===String subset - characters from an arbitrary position in the string===
  
 
'''Mid$(string, start, size)'''  
 
'''Mid$(string, start, size)'''  
  
−
Retrieves a substring from the string starting at position start of size characters.
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Retrieves a substring from the string starting at position start of size characters. The first character of the string is at position zero.
  
 
If the length of the string used to store the result is less than size of the substring returned then any extra characters are lost.
 
If the length of the string used to store the result is less than size of the substring returned then any extra characters are lost.
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TestStr is now "llo"
 
TestStr is now "llo"
  
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===String comparisons===
  
 
'''Compare$(string1, string2, compare_type)'''  
 
'''Compare$(string1, string2, compare_type)'''  
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RetVal is now 0 as both strings are identical.
 
RetVal is now 0 as both strings are identical.
  
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{{Fcfile|StringCompare.fcfx|String Compare Example}}
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===Converting a floating point value/variable to a string===
  
 
'''FloatToString$( float )'''
 
'''FloatToString$( float )'''
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string = FloatToString( float )
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string = FloatToString$( float )
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===Converting a numeric value/variable to a hex string===
  
 
'''NumberToHex$( number )'''
 
'''NumberToHex$( number )'''
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string = FloatToString( INT )
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string = FloatToString$( INT )
  
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===Converting a string to a numeric value/variable===
  
 
'''StringToInt$(string)'''
 
'''StringToInt$(string)'''
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number = StringToInt$( string )  
 
number = StringToInt$( string )  
  
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===Converting a string into a floating point value/variable===
  
 
'''StringToFloat$( string )'''
 
'''StringToFloat$( string )'''

Latest revision as of 13:36, 25 August 2020

See Calculation Icon Properties

String Functions

The String functions are a set of string manipulation functions that can be used to edit, change and examine the strings.

To add a function, drag it into the calculation box. The user can then edit this base code with the variables required.


Btn Calculation.gif → Gen Calculation Flowchart Icon 01.png → Gen StringFunctions 01.jpg


Example Strings used in explaining the functions below:

Str1[20]

Str2[20]

TestStr[40]


Assigning Strings

=

To assign a string value to a string variable you can simply use the = character.

Str1 = "Hello "

Str2 = "World"


Strings can also be treated like byte arrays to allow you to manipulate the individual bytes. For string data to work correctly with other string functions the end of the data must be signified with a 0 or null byte.

Str1[0] = 'H'

Str1[1] = 'e'

Str1[2] = 'l'

Str1[3] = 'l'

Str1[4] = 'o'

Str1[5] = ' '

Str1[6] = 0


Assigning a string constant to a string variable will automatically add the null byte to the end of the string for you.


Str1 = "Hello "


Strings can also be used with escape characters such as \n (newline), \r (carriage return), \t (tab), \xXX (hexadecimal byte value), \\ single backslash character.

Str1 = "Hello\n\rWorld"


Concatenating Strings

+

Concatenates the two string together in the order presented from left to right.

If the resulting string is longer than the array size of the receiving string then any extra characters are lost.


Str1 = "Hello "

Str2 = "World"

TestStr = Str1 + Str2


TestStr is now "Hello World"


Multiple concatenations are best done like this to avoid using excess memory. Note that each line contains only two values to be added together.

TestStr = "Multiple " + Str1

TestStr = TestStr + Str2


TestStr is now "Multiple Hello World"


NOTE: Due to a limitation in generated code the result of multiple concatenations in one operation is limited to 20 characters. So the result of Str1 + Str2 + Str3 should not exceed 20 characters.


Converting a numeric value/variable to a string

ToString$(value)

Changes the numeric value to a String.


TestStr = ToString$(1234)


TestStr is now "1234"


Converting a string to upper case

ToUpper$(string)

Changes all letters to upper case.


TestStr = ToUpper$(Str1)


TestStr is now "HELLO "


Converting a string to lower case

ToLower$(string)

Changes all letters to lower case.


TestStr = ToLower$(Str1)


TestStr is now "hello "


Finding the length of a string

Length$(string)

Retrieves the length of the string.

This is not the Array size, but the number of characters in the array before a Null character is encountered.


RetVal = Length$(Str1)


RetVal is now 6


Note: Str1 array size is 20, but has a String of only 6 characters currently assigned to it hence the return value of 6.


Getting a single character from a string

Char$(string, number)

Retrieves a single byte from the specified position in the string.

Str1= "hello"

RetVal = Char$(Str1, 0)

Retval is now 'H'.


RetVal = Char$(Str1, 4)

Retval is now 'o'.


RetVal = Char$(Str1, 5)

Retval is now 0 (NULL terminator to mark the end of valid data).


String bytes can also be accessed directly using standard C square bracket array notation.

RetVal = Str1[4]

Retval is now 'o'.


String subset - characters from the start of the string

Left$(string, size) Retrieves a substring from the string of size characters starting from the leftmost character.

If the length of the string used to store the result is less than size of the substring returned then any extra characters are lost.


TestStr = Left$(Str1, 3)


TestStr is now "Hel"


String subset - characters from the end of the string

Right$(string, size)

Retrieves a substring from the string of size characters starting from the rightmost character.

i.e. a size of 4 retrieves the 4 rightmost characters.

If the length of the string used to store the result is less than size of the substring returned then any extra characters are lost.


TestStr = Right$(Str1, 3)


TestStr is now "lo "


String subset - characters from an arbitrary position in the string

Mid$(string, start, size)

Retrieves a substring from the string starting at position start of size characters. The first character of the string is at position zero.

If the length of the string used to store the result is less than size of the substring returned then any extra characters are lost.


TestStr = Mid$(Str1, 2, 3)


TestStr is now "llo"


String comparisons

Compare$(string1, string2, compare_type)

Compares the two strings, parameters 1 and 2, and returns a BYTE value corresponding to the following results:


0 = strings are identical

1 = string1>string2

255 = string2>string1


The 3rd parameter, compare_type, determines whether or not the check is case sensitive. values for compare_type are:

0 = case sensitive

1 = case insensitive.

Examples


Str1 = "ABC"

Str2 = "abc"


RetVal = Compare$(Str1, Str2, 0)


RetVal is now 255 as Str2 is later in the ASCII sequence.


RetVal = Compare$(Str1, Str2, 1)


RetVal is now 0 as when case insensitive the two strings are identical.


Str2 = Str1

RetVal = Compare$(Str1, Str2, 0)


RetVal is now 0 as both strings are identical.


FC6 Icon.png String Compare Example


Converting a floating point value/variable to a string

FloatToString$( float )

Converts a floating point number into a string.


float = Floating point number to convert.

string = String variable to hold the conversion data.


string = FloatToString$( float )


Converting a numeric value/variable to a hex string

NumberToHex$( number )

Converts a byte or int number into a hexadecimal string.


number = byte or integer number to convert.

string = String variable to hold the conversion data.


string = FloatToString$( INT )


Converting a string to a numeric value/variable

StringToInt$(string)

Converts a string of numeric ASCII data into an integer numeric data value.


string = String variable containing numeric ASCII data.

returns numeric data from the string in decimal form.


number = StringToInt$( string )


Converting a string into a floating point value/variable

StringToFloat$( string )

Converts a string of numeric ASCII data into a floating point variable.


string = String variable containing numeric ASCII data.

returns numeric data from the string in floating point form.


float = StringToFloat$( string )

Retrieved from "https://www.matrixtsl.com/wiki/index.php?title=String_Manipulation_Functions&oldid=23988"