What is difference between translate and replace in XPath

Question

I was going through some XSLT functions and came across two majorly named as translate and replace, I understood that, by the end of the day, job of both the functions is replacing some content on declared entity (please enlighten me more on this).

Also I was writing an XSLT where in I want to replace a single value with a bunch of values like below.

<div class="translate">
            <xsl:value-of select="translate(current(),' ', 'XXXXX')"/>
        </div>
        <div class="replace">
            <xsl:value-of select="replace(current(),' ', 'XXXXX')"/>
        </div>

The translate is adding only one X, though I've added XXXXX, where as the replace is working fine.

Can someone please let me know what's happening in the background?

Here is a working Sample http://xsltransform.net/6rewNxE/2

Answer 1

The replace-function replaces one string with another in a string. If there is the String "abcacb" and you replace "ab" with "xy" you get "xycacb".

replace("abcacb","ab","xy") = "xycacb"

The translate function replaces the string charcter by character. The first character in the "please-replace-this-string" will be replaced with the first character in "replace-with-this-string" So if there is the String "abcacb" and you translate "ab" with "xy" you get "xycxcy".

translate("abcacb","ab","xy") = "xycxcy"

For your case:

• replace: ' ' will be replaced with 'XXXXX'
• translate ' ' will be replaced with the first character of 'XXXXXX' which is 'X'

The explanations of the Oracle-SQL functions might also help (basically the same):

• replace()
• translate()

Answer 2

Difference between translate() and replace()

• Use translate($s, $mapFrom, $mapTo) to change occurrences of characters given in $mapFrom to those in equivalent positions in $mapTo.
• Use replace($s, $pattern, $replacement) to change occurrences of matching substrings given by a matching $pattern regex to a $replacement string.

Note that translate() is available starting from XPath 1.0; replace(), from XPath 2.0.

Therefore, in your example:

• translate() will replace each ' ' (space) character with a 'X' character, because the $mapTo character that corresponds to the equivalent position of ' ' (space) in the $mapFrom is an 'X'.
• replace() will replace the first " " (single-space) substring with a "XXXXX", because the literal $pattern matches the first occurrence of a " " (single-space) substring and replaces it with the full $replacement string.