Variables, Data Types & Scopes

Data types

ColdFusion is dynamically typed. Variables are created on assignment and their type is inferred at runtime — no int, String, or var declarations required.

CFML's six core data types — dynamically inferred at runtime, no explicit type declarations needed.

Activity: Create data_types.cfm to explore all six data types.

Terminal tab:

sudo tee /opt/coldfusion2025/cfusion/wwwroot/student/data_types.cfm << 'EOF'
<cfscript>
  // String
  myString = "Hello ColdFusion";
  writeOutput("<strong>String:</strong> " & myString & "<br>");

  // Numeric
  myInt  = 42;
  myFloat = 3.14;
  writeOutput("<strong>Numeric:</strong> " & myInt & " / " & myFloat & "<br>");

  // Boolean
  isActive = true;
  writeOutput("<strong>Boolean:</strong> " & isActive & "<br>");

  // Date
  today = now();
  writeOutput("<strong>Date:</strong> " & dateFormat(today, "yyyy-mm-dd") & "<br>");

  // Array
  fruits = ["apple", "banana", "cherry"];
  writeOutput("<strong>Array[1]:</strong> " & fruits[1] & "<br>");

  // Struct
  person = {name: "Alex", age: 30};
  writeOutput("<strong>Struct:</strong> " & person.name & " is " & person.age & "<br>");
</cfscript>
EOF

✏️ Using the IDE tab instead? Create the file here

In the IDE tab, click File → Open Folder…, type /opt/coldfusion2025/cfusion/wwwroot/student and press Enter. If VS Code asks "The folder does not exist. Would you like to create it?" — click Yes. Then right-click in the Explorer panel → New File → name it data_types.cfm, paste the content below, and save with Ctrl+S:

VS Code will offer to create the student folder — click Yes.

<cfscript>
  // String
  myString = "Hello ColdFusion";
  writeOutput("<strong>String:</strong> " & myString & "<br>");

  // Numeric
  myInt  = 42;
  myFloat = 3.14;
  writeOutput("<strong>Numeric:</strong> " & myInt & " / " & myFloat & "<br>");

  // Boolean
  isActive = true;
  writeOutput("<strong>Boolean:</strong> " & isActive & "<br>");

  // Date
  today = now();
  writeOutput("<strong>Date:</strong> " & dateFormat(today, "yyyy-mm-dd") & "<br>");

  // Array
  fruits = ["apple", "banana", "cherry"];
  writeOutput("<strong>Array[1]:</strong> " & fruits[1] & "<br>");

  // Struct
  person = {name: "Alex", age: 30};
  writeOutput("<strong>Struct:</strong> " & person.name & " is " & person.age & "<br>");
</cfscript>

Copy to clipboard

data_types.cfm saved in the student/ folder — ready to run.

Open /data_types.cfm in the ColdFusion 2025 browser tab (right-click → Open Link in New Tab, then change the path). Or from the Terminal:

curl -s http://localhost:8500/student/data_types.cfm

All six data types rendered — each line shows the type name and its value.

Variable scopes

ColdFusion organises variables into named scopes. Every scope has a different lifetime and visibility.

The variables scope is the default when you omit a prefix. Always prefix session.* and application.* explicitly.

Scope lifetimes compared — request-scoped variables are cheapest; application-scoped variables persist for the life of the process.

Activity: Create scopes.cfm to demonstrate the variables scope.

Terminal tab:

sudo tee /opt/coldfusion2025/cfusion/wwwroot/student/scopes.cfm << 'EOF'
<cfscript>
  // variables scope — explicit prefix
  variables.name    = "Alex";
  variables.course  = "ColdFusion 2025";

  writeOutput("<strong>variables.name:</strong> "   & variables.name   & "<br>");
  writeOutput("<strong>variables.course:</strong> " & variables.course & "<br>");

  // url scope — reads ?name= from the query string
  urlName = url.name ?: "no name passed";
  writeOutput("<strong>url.name:</strong> " & urlName & "<br>");
</cfscript>
EOF

<cfscript>
  // variables scope — explicit prefix
  variables.name    = "Alex";
  variables.course  = "ColdFusion 2025";

  writeOutput("<strong>variables.name:</strong> "   & variables.name   & "<br>");
  writeOutput("<strong>variables.course:</strong> " & variables.course & "<br>");

  // url scope — reads ?name= from the query string
  urlName = url.name ?: "no name passed";
  writeOutput("<strong>url.name:</strong> " & urlName & "<br>");
</cfscript>

scopes.cfm saved in the student/ folder — ready to run.

Open /scopes.cfm in the browser to confirm the variables scope output:

curl -s http://localhost:8500/student/scopes.cfm

scopes.cfm with no query string — variables.* values are set, url.name falls back to the default.

Now verify that the variables. prefix is used explicitly in the file:

URL scope

Pass a query-string parameter and read it back with url.name:

curl -s "http://localhost:8500/student/scopes.cfm?name=TestUser"
# Expected: url.name: TestUser

Or in the browser, append ?name=TestUser to the URL:

https://<your-session-id>.iximiuz.com/scopes.cfm?name=TestUser

With ?name=TestUser appended, url.name resolves to TestUser instead of the default.

Scope resolution order

When you omit a scope prefix, CF walks this resolution chain top-to-bottom — always prefix to be explicit.

When you write just name without a prefix, ColdFusion checks scopes in this order:

1. local (inside a CFC function)
2. arguments
3. thread
4. query (inside a <cfloop query="...">)
5. variables
6. cgi, file, url, form, cookie, client

Always prefix to be explicit and avoid scope-bleed bugs. In a large application, an unqualified variable that accidentally resolves from url instead of variables can cause hard-to-trace security issues.

Inspecting scopes with cfdump

ColdFusion has a built-in debugging tool — <cfdump>. It renders any variable, struct, array, query, or entire scope as a colour-coded HTML table directly in the browser. It is the fastest way to see exactly what is in scope at runtime.

<cfdump var="#variables#" label="variables scope">
<cfdump var="#url#"       label="url scope">
<cfdump var="#session#"   label="session scope">

Rule of thumb: add <cfdump> while you develop, remove it before going to production. Leaving it in exposes internal variable names and values to anyone who can reach the page.

Activity: Create cfdump_demo.cfm to dump the variables and url scopes side by side.

Terminal tab:

sudo tee /opt/coldfusion2025/cfusion/wwwroot/student/cfdump_demo.cfm << 'EOF'
<cfscript>
  variables.greeting = "Hello from cfdump";
  variables.counter  = 42;
</cfscript>

<cfdump var="#variables#" label="variables scope">
<cfdump var="#url#"       label="url scope">
EOF

<cfscript>
  variables.greeting = "Hello from cfdump";
  variables.counter  = 42;
</cfscript>

<cfdump var="#variables#" label="variables scope">
<cfdump var="#url#"       label="url scope">

Open /cfdump_demo.cfm in the ColdFusion 2025 browser tab to see the rendered dump tables. Or confirm from the Terminal that the response contains the expected variable names:

curl -s http://localhost:8500/student/cfdump_demo.cfm | grep -i "greeting"
# Expected: a line containing "greeting"

<cfdump> renders each scope as a formatted table — instantly shows every variable name and value at runtime.

Regionalization & locale-aware output

ColdFusion has two sets of formatting functions:

The ls prefix stands for locale-specific. Switch the locale for a request with setLocale() and read it back with getLocale(). The locale only applies for the duration of the current request — it does not persist to the next one.

// Set the locale for this request
setLocale("German (Standard)");

price  = 1234567.89;
today  = now();

writeOutput(lsNumberFormat(price)   & "<br>"); // 1.234.567,89
writeOutput(lsCurrencyFormat(price) & "<br>"); // 1.234.567,89 €
writeOutput(lsDateFormat(today, "long") & "<br>"); // e.g. 3. September 2026

Common locale strings accepted by setLocale():

Gotcha: setLocale() accepts the locale display name as a string, not an IETF tag like en-US. Use getLocaleInfo() to inspect the full list of locales available on the running JVM.

Activity: Create locale_demo.cfm to compare the same number and date formatted in three different locales side by side.

Terminal tab:

sudo tee /opt/coldfusion2025/cfusion/wwwroot/student/locale_demo.cfm << 'EOF'
<cfscript>
  price = 1234567.89;
  today = now();

  locales = [
    "English (US)",
    "German (Standard)",
    "French (Standard)"
  ];

  for (loc in locales) {
    setLocale(loc);
    writeOutput("<strong>" & loc & "</strong><br>");
    writeOutput("&nbsp;&nbsp;Number:   " & lsNumberFormat(price)          & "<br>");
    writeOutput("&nbsp;&nbsp;Currency: " & lsCurrencyFormat(price)        & "<br>");
    writeOutput("&nbsp;&nbsp;Date:     " & lsDateFormat(today, "long")    & "<br><br>");
  }
</cfscript>
EOF

<cfscript>
  price = 1234567.89;
  today = now();

  locales = [
    "English (US)",
    "German (Standard)",
    "French (Standard)"
  ];

  for (loc in locales) {
    setLocale(loc);
    writeOutput("<strong>" & loc & "</strong><br>");
    writeOutput("&nbsp;&nbsp;Number:   " & lsNumberFormat(price)          & "<br>");
    writeOutput("&nbsp;&nbsp;Currency: " & lsCurrencyFormat(price)        & "<br>");
    writeOutput("&nbsp;&nbsp;Date:     " & lsDateFormat(today, "long")    & "<br><br>");
  }
</cfscript>

Open /locale_demo.cfm in the ColdFusion 2025 browser tab, or from the Terminal:

curl -s http://localhost:8500/student/locale_demo.cfm

You should see three blocks — each showing the same number and date formatted differently:

English (US)
  Number:   1,234,567.89
  Currency: $1,234,567.89
  Date:     September 3, 2026

German (Standard)
  Number:   1.234.567,89
  Currency: 1.234.567,89 €
  Date:     3. September 2026

French (Standard)
  Number:   1 234 567,89
  Currency: 1 234 567,89 €
  Date:     3 septembre 2026

vi /opt/coldfusion2025/cfusion/wwwroot/student/scopes.cfm

When all the checks above are green, this lesson is complete. Your progress is saved automatically — move straight on to the next lesson.

The raw curl response from cfdump_demo.cfm — the greeting variable is visible in the output, confirming the dump ran correctly.