Pattern catalog

Patterns are common ways of doing things, like recipes. People have patterns for solving equations, making web pages, wrapping gifts, all sorts of things. Part of learning a skill is learning the patterns that help you be more effective.

Here are patterns on this website. This list can help you find the patterns you need to do a task.

Name	Situation	Tags	Action	Where referenced
Normalize a variable	You have a variable that can have many formats, maybe leading and trailing spaces, and upper- and lowercase. You want to test the variable with an `If`.	Variables	Convert a variable that can have many formats, into one format. Needs: A variable that can have many formats. Provides: A variable in a single format.	Normalizing, Basic validation: strings, Logical operators
Numeric type check	You want to check whether a value is a valid number.	Validation	Put a value into a string. Use the `IsNumeric()` function. Needs: A value to check. Provides: A variable that you know is a number.	Basic validation: numeric
Output to a cell	You want to show the user some output.	Output	Copy a value to a cell in a worksheet. Needs: A variable with a value in it. The row and column of the cell that the value will be copied into. Provides: A happy user.<br /> <br /> <br />	Generalize
Output to a dialog	You want to show a message to a user. Could be a variable's value, an error message, or something else.	Output	Use a `MsgBox` to show a dialog box. Needs: A message to show. Might include a variable's value. Provides: Happy user.
Range check	You have a number that might be too small, or too high. You want to check it, to make sure it's OK.	Validation, If	Check whether a number is between two other numbers. Warning: "range" has two meanings. This pattern is not about `Range` objects. Needs: Minimum, maximum, and a value to check. Provides: A validated number, or an error.	Basic validation: numeric, Logical operators
Sequence	You need to do a simple computation.		A simple sequence of statements. Needs: Some variables whose values need to be changed. Provides: Variables with changed values.
Validation (better)	You have several pieces of data to check. You want to show all the errors at once.	Validation	Wrap a bunch of individual checks inside the flag pattern. Needs: Several pieces of data you don't trust. Provides: Checked data you can work with.	Better validation
Validation (numeric, basic)	You have some data that's supposed to be numeric. Could be from a cell, a file, a dialog box, wherevs. You want to check the data.	Validation	Test that data is numeric. Add range checks and other tests, as needed. Needs: A data value. Provides: Number that's valid, or an error message.
Validation (string, basic)	You have some string data you don't trust. Could be from a cell, a file, a dialog box, wherevs. You want to check the data.	Validation	Normalize, then test with `If`(s). Needs: Some string data. Provides: String data that's valid, or an error message.	Basic validation: strings
Variable increase/decrease	You are accumulating a value, like a total, or count.		An assignment statement, like `sTotal = sTotal + sSales`. Adds to a variable, then puts the result back in the variable. Needs: A variable to be increased/decreased, and a value to add or subtract. Provides: A variable that has been increased/decreased.	Numeric expressions