C's string.strcat in TypeScript

How to use

Install via yarn add locutus and import: import { strcat } from 'locutus/c/string/strcat'.

Or with CommonJS: const { strcat } = require('locutus/c/string/strcat')

Use a bundler that supports tree-shaking so you only ship the functions you actually use. Vite, webpack, Rollup, and Parcel all handle this. For server-side use this is less of a concern.

Examples

These examples are extracted from test cases that automatically verify our functions against their native counterparts.

#	code	expected result
1	strcat('Hello, ', 'World!')	'Hello, World!'
2	strcat('abc', 'def')	'abcdef'

C types and TypeScript/JavaScript

C is statically typed while TypeScript/JavaScript is dynamically typed. Locutus C functions accept TypeScript/JavaScript's flexible types but are only parity-verified for inputs that would be valid in C.

For example, abs() in TypeScript/JavaScript accepts floats (like C's fabs()) and handles strings gracefully, but only integer inputs are verified against native C. This pragmatic approach gives you the expected C behavior for valid inputs while leveraging TypeScript/JavaScript's flexibility for edge cases.

Notes

• Appends src string to dest string. In C this modifies dest, but JS strings are immutable so we return a new string.

Here's what our current TypeScript equivalent to C's strcat found in the string.h header file looks like.

TSTypeScript JSJavaScript TSStandalone TS JSStandalone JS

Copy code

export function strcat(dest: string, src: string): string {
  //  discuss at: https://locutus.io/c/string/strcat/
  // original by: Kevin van Zonneveld (https://kvz.io)
  //      note 1: Appends src string to dest string.
  //      note 1: In C this modifies dest, but JS strings are immutable so we return a new string.
  //   example 1: strcat('Hello, ', 'World!')
  //   returns 1: 'Hello, World!'
  //   example 2: strcat('abc', 'def')
  //   returns 2: 'abcdef'

  return dest + '' + (src + '')
}

export function strcat(dest, src) {
  //  discuss at: https://locutus.io/c/string/strcat/
  // original by: Kevin van Zonneveld (https://kvz.io)
  //      note 1: Appends src string to dest string.
  //      note 1: In C this modifies dest, but JS strings are immutable so we return a new string.
  //   example 1: strcat('Hello, ', 'World!')
  //   returns 1: 'Hello, World!'
  //   example 2: strcat('abc', 'def')
  //   returns 2: 'abcdef'

  return dest + '' + (src + '')
}

Improve this function

Locutus is a community effort following The McDonald's Theory: we ship first iterations, hoping others will improve them. If you see something that could be better, we'd love your contribution.

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We have 20 C functions so far - help us add more

Got a rainy Sunday afternoon and a taste for a porting puzzle?

• Get inspiration from the C math.h documentation, the C math.h source.
• Click "New file" in the appropriate folder on GitHub. This will fork the project to your account, directly add the file to it, and send a Pull Request to us.

We will then review it. If it's useful to the project and in line with our contributing guidelines your work will become part of Locutus and you'll be automatically credited in the authors section accordingly.

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