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StringInsert—Wolfram Documentation

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StringInsert["string","snew",n]

yields a string with "snew" inserted starting at position n in "string".

StringInsert["string","snew",-n]

inserts at position n from the end of "string".

StringInsert["string","snew",{n1,n2,…}]

inserts a copy of "snew" at each of the positions ni.

StringInsert[{s1,s2,…},"snew",n]

gives the list of results for each of the si.

Details
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Applications  
Properties & Relations  
Possible Issues  
See Also
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StringInsert

StringInsert["string","snew",n]

yields a string with "snew" inserted starting at position n in "string".

StringInsert["string","snew",-n]

inserts at position n from the end of "string".

StringInsert["string","snew",{n1,n2,…}]

inserts a copy of "snew" at each of the positions ni.

StringInsert[{s1,s2,…},"snew",n]

gives the list of results for each of the si.

Details

  • StringInsert["string","snew",n] makes the first character of snew the n^(th) character in the new string.
  • StringInsert["string","snew",-n] makes the last character of snew the n^(th) character from the end of the new string.
  • In StringInsert["string","snew",{n1,n2,…}] the ni are taken to refer to positions in "string" before any insertion is done. »
  • StringInsert[BioSequence["type","seq"],…] will apply the operation to the string "seq", yielding a BioSequence result.

Examples

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Basic Examples  (1)

Insert "XYZ" at character position 4:

Wolfram Language code: StringInsert["abcdefghijklm", "XYZ", 4]

Scope  (3)

Insert "XYZ" starting 4 character positions from the end of the string:

Wolfram Language code: StringInsert["abcdefghijklm", "XYZ", -4]

Insert "XYZ" at several positions:

Wolfram Language code: StringInsert["abcdefghijklm", "XYZ", {2, 3, 7}]

Insert into a biomolecular sequence:

Wolfram Language code: StringInsert[BioSequence["DNA", "GCCCGAGAC"], "TTT", 2]

Applications  (1)

Insert a dot at every third character position:

Wolfram Language code: StringInsert["1234567890123456", ".", Range[4, 16, 3]]

Count from the end:

Wolfram Language code: StringInsert["1234567890123456", ".", Range[-16, -4, 3]]

Properties & Relations  (2)

Insertion positions always refer to the original string:

Wolfram Language code: StringInsert["abc", "XYZ", {1, 2, 3}]

Insert "XYZ" to start one character position after the end of the existing string:

Wolfram Language code: StringInsert["abcd", "XYZ", 5]

An equivalent form:

Wolfram Language code: StringInsert["abcd", "XYZ", -1]

Possible Issues  (2)

The positions refer to the original string, not the final one:

Wolfram Language code: StringInsert["abcdefghijklm", "XYZ", {2, 3, 7}]
Wolfram Language code: StringPosition[%, "XYZ"]

StringInsert operates on the raw characters in a string:

Wolfram Language code: StringInsert["red", "XYZ", 10]
Wolfram Language code: FullForm["red"]
Wolfram Research (1991), StringInsert, Wolfram Language function, https://reference.wolfram.com/language/ref/StringInsert.html (updated 2020).

Text

Wolfram Research (1991), StringInsert, Wolfram Language function, https://reference.wolfram.com/language/ref/StringInsert.html (updated 2020).

CMS

Wolfram Language. 1991. "StringInsert." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2020. https://reference.wolfram.com/language/ref/StringInsert.html.

APA

Wolfram Language. (1991). StringInsert. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/StringInsert.html

BibTeX

@misc{reference.wolfram_2026_stringinsert, author="Wolfram Research", title="{StringInsert}", year="2020", howpublished="\url{https://reference.wolfram.com/language/ref/StringInsert.html}", note=[Accessed: 14-November-2026]}

BibLaTeX

@online{reference.wolfram_2026_stringinsert, organization={Wolfram Research}, title={StringInsert}, year={2020}, url={https://reference.wolfram.com/language/ref/StringInsert.html}, note=[Accessed: 14-November-2026]}