# MATLAB - The for Loop

A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times.

## Syntax

The syntax of a for loop in MATLAB is −

```for index = values
<program statements>
...
end
```

values has one of the following forms −

Format Description
initval:endval increments the index variable from initval to endval by 1, and repeats execution of program statements until index is greater than endval.
initval:step:endval increments index by the value step on each iteration, or decrements when step is negative.
valArray creates a column vector index from subsequent columns of array valArray on each iteration. For example, on the first iteration, index = valArray(:,1). The loop executes for a maximum of n times, where n is the number of columns of valArray, given by numel(valArray, 1, :). The input valArray can be of any MATLAB data type, including a string, cell array, or struct.

## Example 1

Create a script file and type the following code −

```for a = 10:20
fprintf('value of a: %d\n', a);
end
```

When you run the file, it displays the following result −

```value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 15
value of a: 16
value of a: 17
value of a: 18
value of a: 19
value of a: 20
```

## Example 2

Create a script file and type the following code −

```for a = 1.0: -0.1: 0.0
disp(a)
end
```

When you run the file, it displays the following result −

``` 1
0.90000
0.80000
0.70000
0.60000
0.50000
0.40000
0.30000
0.20000
0.10000
0
```

## Example 3

Create a script file and type the following code −

```for a = [24,18,17,23,28]
disp(a)
end
```

When you run the file, it displays the following result −

```24

18

17

23

28
```

matlab_loops.htm