By default, when you call the worksheet's `setCellValue()` method or the cell's `setValue()` method, PhpSpreadsheet will use the appropriate datatype for PHP nulls, booleans, floats or integers; or cast any string data value that you pass to the method into the most appropriate datatype, so numeric strings will be cast to numbers, while string values beginning with “=” will be converted to a formula. Strings that aren't numeric, or that don't begin with a leading "=" will be treated as genuine string values.
This "conversion" is handled by a cell "value binder", and you can write custom "value binders" to change the behaviour of these "conversions". The standard PhpSpreadsheet package also provides an "advanced value binder" that handles a number of more complex conversions, such as converting strings with a fractional format like "3/4" to a number value (0.75 in this case) and setting an appropriate "fraction" number format mask. Similarly, strings like "5%" will be converted to a value of 0.05, and a percentage number format mask applied, and strings containing values that look like dates will be converted to Excel serialized datetimestamp values, and a corresponding mask applied. This is particularly useful when loading data from csv files, or setting cell values from a database.
Date or time values are held as timestamp in Excel (a simple floating point value), and a number format mask is used to show how that value should be formatted; so if we want to store a date in a cell, we need to calculate the correct Excel timestamp, and set a number format mask.
```php
// Get the current date/time and convert to an Excel date/time
By default, PhpSpreadsheet will automatically detect the value type and set it to the appropriate Excel numeric datatype. This type conversion is handled by a value binder, as described in the section of this document entitled "Using value binders to facilitate data entry".
Numbers don't have leading zeroes, so if you try to set a numeric value that does have leading zeroes (such as a telephone number) then these will be normally be lost as the value is cast to a number, so "01513789642" will be displayed as 1513789642.
**Note** that not all complex format masks such as this one will work when retrieving a formatted value to display "on screen", or for certain writers such as HTML or PDF, but it will work with the true spreadsheet writers (Xlsx and Xls).
If you pass a 2-d array, then this will be treated as a series of rows and columns. A 1-d array will be treated as a single row, which is particularly useful if you're fetching an array of data from a database.
If you have a simple 1-d array, and want to write it as a column, then the following will convert it into an appropriately structured 2-d array that can be fed to the `fromArray()` method:
To retrieve the value of a cell, the cell should first be retrieved from the worksheet using the `getCell()` method. A cell's value can be read using the `getValue()` method.
This will retrieve the raw, unformatted value contained in the cell.
If a cell contains a formula, and you need to retrieve the calculated value rather than the formula itself, then use the cell's `getCalculatedValue()` method. This is further explained in .
Alternatively, if you want to see the value with any cell formatting applied (e.g. for a human-readable date or time value), then you can use the cell's `getFormattedValue()` method.
**Note** that column references start with '0' for column 'A', rather than from '1'.
### Retrieving a cell value by column and row
To retrieve the value of a cell, the cell should first be retrieved from the worksheet using the getCellByColumnAndRow method. A cell’s value can be read again using the following line of code:
It is also possible to retrieve a range of cell values to an array in a single call using the `toArray()`, `rangeToArray()` or `namedRangeToArray()` methods.
'C3:E5', // The worksheet range that we want to retrieve
NULL, // Value that should be returned for empty cells
TRUE, // Should formulas be calculated (the equivalent of getCalculatedValue() for each cell)
TRUE, // Should values be formatted (the equivalent of getFormattedValue() for each cell)
TRUE // Should the array be indexed by cell row and cell column
);
```
These methods will all return a 2-d array of rows and columns. The `toArray()` method will return the whole worksheet; `rangeToArray()` will return a specified range or cells; while `namedRangeToArray()` will return the cells within a defined `named range`.
### Looping through cells
#### Looping through cells using iterators
The easiest way to loop cells is by using iterators. Using iterators, one can use foreach to loop worksheets, rows within a worksheet, and cells within a row.
Below is an example where we read all the values in a worksheet and display them in a table.
Note that we have set the cell iterator's `setIterateOnlyExistingCells()` to FALSE. This makes the iterator loop all cells within the worksheet range, even if they have not been set.
The cell iterator will return a __NULL__ as the cell value if it is not set in the worksheet.
Setting the cell iterator's setIterateOnlyExistingCells() to FALSE will loop all cells in the worksheet that can be available at that moment. This will create new cells if required and increase memory usage! Only use it if it is intended to loop all cells that are possibly available.
#### Looping through cells using indexes
One can use the possibility to access cell values by column and row index like (0,1) instead of 'A1' for reading and writing cell values in loops.
Note that we can't use a <= comparison here, because 'AA' would match as <= 'B', so we increment the highest column letter and then loop while $col != the incremented highest column.
Internally, PhpSpreadsheet uses a default \PhpOffice\PhpSpreadsheet\Cell\IValueBinder implementation (\PhpOffice\PhpSpreadsheet\Cell\DefaultValueBinder) to determine data types of entered data using a cell's `setValue()` method (the `setValueExplicit()` method bypasses this check).
Optionally, the default behaviour of PhpSpreadsheet can be modified, allowing easier data entry. For example, a \PhpOffice\PhpSpreadsheet\Cell\AdvancedValueBinder class is available. It automatically converts percentages, number in scientific format, and dates entered as strings to the correct format, also setting the cell's style information. The following example demonstrates how to set the value binder in PhpSpreadsheet:
When advanced value binding is required, you can implement the \PhpOffice\PhpSpreadsheet\Cell\IValueBinder interface or extend the \PhpOffice\PhpSpreadsheet\Cell\DefaultValueBinder or \PhpOffice\PhpSpreadsheet\Cell\AdvancedValueBinder classes.
