How do I replace a string in an Excel array if it is found in a column?

To replace a string within an Excel array (or table column) if that string is found, you can use a combination of Excel formulas. Here's how:

Scenario: Suppose you have a column (let's say column A) of text values, and you want to replace a specific string (e.g., "oldValue") with another string (e.g., "newValue") if "oldValue" exists within any cell in the column.

Method: Using Excel Formulas

1. Using the `IF`, `ISNUMBER`, and `FIND` functions: This is the most common method to check for a string and conditionally replace it:

- In another column (say column B), enter the following formula in the first row and drag it down:

=IF(ISNUMBER(FIND("oldValue",A1)),SUBSTITUTE(A1,"oldValue","newValue"),A1)

- Explanation:

- `FIND("oldValue",A1)`: This attempts to find the position of "oldValue" within cell A1. If found, it returns the starting position of the substring. If not found, it returns an error (#VALUE!).

- `ISNUMBER(...)`: This checks if the result of `FIND` is a number (meaning "oldValue" was found). It returns TRUE if found, FALSE otherwise.

- `SUBSTITUTE(A1,"oldValue","newValue")`: If `ISNUMBER` returns TRUE, this replaces all occurrences of "oldValue" with "newValue" in A1.

- `A1`: If `ISNUMBER` returns FALSE, the original value of A1 is returned without changes.

2. Case-Insensitive search: If you need a case-insensitive search, use the `SEARCH` function instead of `FIND`:

=IF(ISNUMBER(SEARCH("oldValue",A1)),SUBSTITUTE(A1,"oldValue","newValue"),A1)

The `SEARCH` function will find "OldValue" or "OLDVALUE" as well as "oldValue".

3. Handling multiple replacements: If you have a list of values to replace, you might need more complex formulas or use VBA. This example is for a single replacement string.

Example:

If A1 contains "This is an oldValue string" and you are replacing "oldValue" with "newValue", the formula in B1 would return "This is an newValue string". If A1 contains "No old value here", B1 will simply output "No old value here".

Alternative method: Using VBA Macro

If you need to do complex string manipulations or operate directly on the source column, VBA (Visual Basic for Applications) could be more appropriate. You would write a VBA macro to loop through the column and apply the replacements in place.

By utilizing these formulas, you can effectively replace strings within an Excel column based on the search criteria.

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