We can replace a substring of characters within a string using a similar method to that demonstrated in Ruby's syntax for substr. This time however we're assigning a new value to positions we specify.
Assign the first five characters of a string:
{{code:php print substr_replace("hello world", "hey", 0, 5); // => hey world }}
{{code:ruby puts "hello world"[0, 5] = "hey" # => hey world }}
Assign all characters after a specified position. In Ruby we can use Ranges to specify a range of character positions:
{{code:php print substr_replace("hello world", "p", 3); // => help }}
{{code:ruby puts "hello world"[3..-1] = "p" # => help }}
Assign the last five characters in the string:
{{code:php print substr_replace("hello world", "p", 3); // => help }}
{{code:ruby puts "hello world"[3..-1] = "p" # => help }}
{{related: strings/str_replace strings/substr }}