The str_replace function takes three input parameters, four actually but the most important is the first three input parameters.
The first one is the character/string that you want to remove/replace, the second is the character/string that will be replacing, the third is the string or variable that contains the string.
str_replace($remove, $replace, $the_string)
$original = 'lets_go_to_the_beach_today_my_friend'; $replace = str_replace('_', ' ', $original); echo $replace;
The code above will output:
lets go to the beach today my friend
If you want, you can also count how many times the string being replaced/removed, using the fourth parameter, let's say $count.
$original = 'lets_go_to_the_beach_today_my_friend'; $replace = str_replace('_', ' ', $original, $count); echo $count;
In mysql database there is a similar function called replace(), which works exactly the same as str_replace() on php, only the parameter position is little different. So if you want to do it on a query you can use mysql replace() function.