In CFML strings are a type of variables that are used to store collections of letters and numbers. Usually defined within single or double quotes (
" ). Some simple strings would be
"This sentence is a string!". Strings can be anything from
"", the empty string, to really long sets of text.
Please note that the underlying type for a string in CFML is the Java String, which is immutable; meaning it can never change. Thus, when concatenating strings together, a new string object is always created. This is a warning that if you will be doing many string concatenations, you will have to use a Java data type to accelerate the concatenations. You have been warned.
In Lucee server you can actually reference characters in a string stream via their position in the string using array syntax:
varname[ position ]. Please note that string and array positions in CFML start at 1 and not 0.
name = "luis"; writeoutput( name ) => will produce l
Common String Functions
You can find all the available string functions here: https://cfdocs.org/string-functions. Below are some common ones that are handy to memorize:
len()on a string to get back the number of characters in the string. For instance
Len( "Hello ")would give you back 6 (notice the trailing space is counted). You can also use member functions:
Triminstruction removes leading and trailing spaces and control characters from a string. For instance
Trim("Hello ")would give you back
Hello(notice the trailing space is removed). Combine this with
Len( Trim( "Hello ") )and you would get back
5. You can also use member functions:
Replaceinstruction replaces occurrences of substring1 in a string with substring2, in a specified scope. The search is case sensitive and the scope default is one. For instance,
Replace("Hello", "l", "")would give you back Helo after replacing the first occurrence of l, or
Replace("Good Morning!", "o", "e", "All")would give you Geed Merning!
RemoveCharsto remove characters from a string. For instance,
RemoveChars("hello bob", 2, 5)would give you back hbob.
midinstruction extracts a substring from a string. For instance, I could call
Mid("Welcome to CFML Jumpstart", 4, 12)and it would give you back: come to CFML.
Another great function is
listToArray() which can take any string and convert it to an array according to a delimiter. The default delimiter is a comma
,, but you can use any 1 or combination of characters.
a = "luis,majano,lucas,alexia,veronica"; myArray = a.listToArray();
Combining Strings and Variables
Combining and interpolating strings is part of any programming language and an integral part. We can do both by building upon some language operators.
If you have 2 or more strings, you can concatenate them by using the
name = "Luis"; a = "Hello " & name & " how are you today?";
Interpolating is where we stick a string within another string. In CFML we use the
# hashes to output a variable to the stream in context. This means we can interpolate into any string:
name = "luis"; welcome = "Good morning #name#, how are you today?"; writeoutput( welcome );
That's it! If you surround any simple variable with
# hashes, CFML will interpret the variable. Now try this with a complex variable and see what happens:
complex = [1,2,3]; welcome = "Good morning #complex#, how are you today?"; writeoutput( welcome );