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Replace Text in DOCX and PPTX

replace_text(needle, replacement) walks every <w:t> element in a DOCX (body, headers, footers) and every <a:t> across every slide and notes-slide in a PPTX. It returns the number of replacements made.

This is the right tool for templating: define {{placeholders}} in your source document, fill them at runtime.

Single-pass replace

Rust

use office_oxide::edit::EditableDocument;

let mut ed = EditableDocument::open("contract.docx")?;
let n = ed.replace_text("{{client_name}}", "Acme Corp");
println!("{n} replacements");
ed.save("contract_acme.docx")?;

Python

from office_oxide import EditableDocument

with EditableDocument.open("contract.docx") as ed:
    n = ed.replace_text("{{client_name}}", "Acme Corp")
    print(f"{n} replacements")
    ed.save("contract_acme.docx")

JavaScript

import { EditableDocument } from 'office-oxide';

using ed = EditableDocument.open('contract.docx');
const n = ed.replaceText('{{client_name}}', 'Acme Corp');
console.log(`${n} replacements`);
ed.save('contract_acme.docx');

Go

ed, _ := officeoxide.OpenEditable("contract.docx")
defer ed.Close()
n, _ := ed.ReplaceText("{{client_name}}", "Acme Corp")
fmt.Printf("%d replacements\n", n)
ed.Save("contract_acme.docx")

C#

using var ed = EditableDocument.Open("contract.docx");
long n = ed.ReplaceText("{{client_name}}", "Acme Corp");
Console.WriteLine($"{n} replacements");
ed.Save("contract_acme.docx");

C

int err = 0;
OfficeEditableHandle *ed = office_editable_open("contract.docx", &err);
int64_t n = office_editable_replace_text(ed, "{{client_name}}", "Acme Corp", &err);
printf("%lld replacements\n", (long long)n);
office_editable_save(ed, "contract_acme.docx", &err);
office_editable_free(ed);

Multi-key fill-in

Apply many replacements before saving — much cheaper than re-opening the file each time.

Rust

let fields = [
    ("{{client_name}}",   "Acme Corp"),
    ("{{contract_date}}", "2026-04-19"),
    ("{{amount}}",        "$120,000"),
    ("{{tier}}",          "Enterprise"),
];

let mut ed = EditableDocument::open("contract.docx")?;
for (needle, value) in fields {
    ed.replace_text(needle, value);
}
ed.save("contract_acme.docx")?;

Python

fields = {
    "{{client_name}}":   "Acme Corp",
    "{{contract_date}}": "2026-04-19",
    "{{amount}}":        "$120,000",
    "{{tier}}":          "Enterprise",
}

with EditableDocument.open("contract.docx") as ed:
    for needle, value in fields.items():
        ed.replace_text(needle, value)
    ed.save("contract_acme.docx")

JavaScript

const fields = {
  '{{client_name}}':   'Acme Corp',
  '{{contract_date}}': '2026-04-19',
  '{{amount}}':        '$120,000',
  '{{tier}}':          'Enterprise',
};

using ed = EditableDocument.open('contract.docx');
for (const [k, v] of Object.entries(fields)) ed.replaceText(k, v);
ed.save('contract_acme.docx');

C

const char *keys[]   = { "{{client_name}}", "{{contract_date}}", "{{amount}}", "{{tier}}" };
const char *values[] = { "Acme Corp",       "2026-04-19",        "$120,000",   "Enterprise" };

int err = 0;
OfficeEditableHandle *ed = office_editable_open("contract.docx", &err);
for (size_t i = 0; i < 4; i++) {
    office_editable_replace_text(ed, keys[i], values[i], &err);
}
office_editable_save(ed, "contract_acme.docx", &err);
office_editable_free(ed);

PPTX templating

Same API, same semantics — replace_text walks every slide and every notes-slide.

Rust

let mut ed = EditableDocument::open("deck_template.pptx")?;
ed.replace_text("{{quarter}}", "Q4 2026");
ed.replace_text("{{growth}}",  "+18.4%");
ed.save("q4_deck.pptx")?;

Python

with EditableDocument.open("deck_template.pptx") as ed:
    ed.replace_text("{{quarter}}", "Q4 2026")
    ed.replace_text("{{growth}}",  "+18.4%")
    ed.save("q4_deck.pptx")

JavaScript

using ed = EditableDocument.open('deck_template.pptx');
ed.replaceText('{{quarter}}', 'Q4 2026');
ed.replaceText('{{growth}}',  '+18.4%');
ed.save('q4_deck.pptx');

Go

ed, _ := officeoxide.OpenEditable("deck_template.pptx")
defer ed.Close()
ed.ReplaceText("{{quarter}}", "Q4 2026")
ed.ReplaceText("{{growth}}", "+18.4%")
ed.Save("q4_deck.pptx")

C#

using var ed = EditableDocument.Open("deck_template.pptx");
ed.ReplaceText("{{quarter}}", "Q4 2026");
ed.ReplaceText("{{growth}}", "+18.4%");
ed.Save("q4_deck.pptx");

C

int err = 0;
OfficeEditableHandle *ed = office_editable_open("deck_template.pptx", &err);
office_editable_replace_text(ed, "{{quarter}}", "Q4 2026", &err);
office_editable_replace_text(ed, "{{growth}}",  "+18.4%", &err);
office_editable_save(ed, "q4_deck.pptx", &err);
office_editable_free(ed);

Notes about run boundaries

DOCX and PPTX split text into “runs” — contiguous spans of identically-styled characters. Word may render {{name}} as three separate runs internally if the user pasted or auto-corrected mid-token. replace_text handles cross-run matches transparently: it merges adjacent runs of the same style window before searching.

If your placeholders use special characters or styled spans, prefer simple ASCII tokens like {{name}} over Word’s “smart quotes” — that minimizes the cross-run merging cost.

XLSX is different

replace_text returns 0 on XLSX because spreadsheet text lives in the shared-strings table and cell formulas, not in <w:t> / <a:t> elements. Use set_cell instead.

See also