To create a simple button with bootstrap the syntax is:
<button type="submit" class="btn btn-default" >Search</button>
Now, to create a button that goes full-width inside a given block, just add the "btn-block" option like so:
<button type="submit" class="btn btn-default btn-block" >Search</button>
Note 1: to center the button: add "text-center"
Note 2: in bootstrap v2, the option was: input-block-level

Source code to get the above example:
<!DOCTYPE html><html lang="en"><head><title>Bootstrap Example</title><meta charset="utf-8"><link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"><script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script><script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script><style>body {padding-top: 50px;background-color:#FFFFF;}</style></head><body><div class="container"><div class="row"><div class="col-md-4"><div class="panel panel-default"><div class="panel-heading"><h4 class="panel-title">Simple Button</h4></div><div class="panel-body"><button type="submit" class="btn btn-default" >Search</button></div></div></div></div><div class="row"><div class="col-md-4"><div class="panel panel-default"><div class="panel-heading"><h4 class="panel-title">Center Button</h4></div><div class="panel-body text-center"><button type="submit" class="btn btn-default" >Search</button></div></div></div></div><div class="row"><div class="col-md-4"><div class="panel panel-default"><div class="panel-heading"><h4 class="panel-title">Full-Width Button</h4></div><div class="panel-body"><button type="submit" class="btn btn-default btn-block" >Search</button></div></div></div></div></div></body></html>
References
| Link | Source |
|---|---|
| Making button go full-width? | stackoverflow |
| Buttons | bootstrap.com |
| How to center buttons in Twitter Bootstrap 3? | stackoverflow |
| How to align button to center using Bootstrap | stackoverflow |
