Environ$ Function

Returns the string value associated with an environment variable.

Syntax

Environ$(envstring)
Environ$(number)

Parameters

• envstring: A string expression containing the name of an environment variable.
• number: A numeric expression corresponding to the numeric order of an environment string in the environment-string table. The number argument can be any numeric expression, but is rounded to a whole number before it is evaluated.

Return Value

Returns a String containing the text assigned to the specified environment variable. If the environment variable doesn't exist, returns an empty string.

Remarks

The Environ$ function returns the string assigned to the specified environment variable from the operating system's environment-string table. This function cannot be used on the left side of an assignment statement.

When using a numeric argument, Environ$ returns the string that occupies that numeric position in the environment table. In this case, Environ$ returns all the text including the equal sign (=). If there's no environment string at the specified position, Environ$ returns a zero-length string.

When using a string argument, if the environment variable doesn't exist, a zero-length string is returned.

Typical Uses

Example 1: Getting System Path

Dim systemPath As String
systemPath = Environ$("PATH")

Example 2: Getting Temp Directory

Dim tempDir As String
tempDir = Environ$("TEMP")

Example 3: Getting User Name

Dim userName As String
userName = Environ$("USERNAME")

Example 4: Iterating Environment Variables

Dim i As Integer
Dim envVar As String
i = 1
Do
envVar = Environ$(i)
If envVar <> "" Then Debug.Print envVar
i = i + 1
Loop While envVar <> ""

Common Usage Patterns

Getting Application Data Path

Dim appDataPath As String
appDataPath = Environ$("APPDATA")
If appDataPath <> "" Then
appDataPath = appDataPath & "\MyApp\"
End If

Getting User Profile Directory

Dim userProfile As String
userProfile = Environ$("USERPROFILE")
configFile = userProfile & "\config.ini"

Checking for Development Environment

Dim devMode As Boolean
devMode = (Environ$("DEV_MODE") = "1")
If devMode Then
Debug.Print "Running in development mode"
End If

Building Full Path with Temp Directory

Dim tempFile As String
tempFile = Environ$("TEMP") & "\tempdata.tmp"
Open tempFile For Output As #1

Getting System Drive

Dim systemDrive As String
systemDrive = Environ$("SystemDrive")
logPath = systemDrive & "\Logs\app.log"

Listing All Environment Variables

Dim idx As Integer
Dim envEntry As String
For idx = 1 To 255
envEntry = Environ$(idx)
If envEntry = "" Then Exit For
List1.AddItem envEntry
Next idx

Cross-Platform Path Separator

Dim pathSep As String
If Environ$("OS") Like "Windows*" Then
pathSep = "\"
Else
pathSep = "/"
End If

Getting Computer Name

Dim computerName As String
computerName = Environ$("COMPUTERNAME")
If computerName = "" Then computerName = Environ$("HOSTNAME")

Building Log File Path with User Name

Dim logFile As String
logFile = "C:\Logs\" & Environ$("USERNAME") & ".log"
Open logFile For Append As #1
Print #1, Now & " - User logged in"
Close #1

Checking if Variable Exists

Dim dbServer As String
dbServer = Environ$("DB_SERVER")
If dbServer = "" Then
dbServer = "localhost"  ' Default value
End If

Related Functions

• Environ: Non-string variant (returns Variant)
• Command$: Gets command-line arguments
• CurDir$: Gets current directory
• GetSetting: Reads application settings from registry
• Dir$: Lists files in directory

Best Practices

1. Always check if the returned value is empty before using it
2. Use string argument form for better code readability
3. Cache frequently accessed environment variables
4. Be aware of case sensitivity on different platforms
5. Avoid modifying environment variables from VB6 (use shell APIs instead)
6. Use proper path combining (avoid double backslashes)
7. Consider using GetEnvironmentVariable API for more control
8. Remember that environment variables persist only for the process lifetime
9. Use constants for commonly used environment variable names
10. Validate paths returned from environment variables before using them

Performance Considerations

• Environment variable lookup is relatively fast
• Iterating all variables with numeric index is slower than direct lookup
• Consider caching values if used frequently in loops
• No significant performance difference between Environ$ and Environ

Platform Differences

Common Environment Variables

Common Pitfalls

• Not checking for empty string return values
• Assuming environment variable names are case-insensitive on all platforms
• Using numeric index without checking for empty string to detect end
• Creating paths with double backslashes when concatenating
• Assuming all common variables exist on all systems
• Not handling missing required environment variables gracefully

Limitations

• Cannot be used to set environment variables (use Windows API)
• Environment changes don't persist beyond process lifetime
• Limited to current process's environment space
• Some variables may be protected or unavailable depending on permissions
• Variable availability differs between operating systems