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Q&A How do I filter an array in C?

No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing. In this challenge in Code ...

2 answers  ·  posted 3y ago by General Sebast1an‭  ·  last activity 3y ago by Derek Elkins‭

Question c javascript array
#7: Post undeleted by user avatar General Sebast1an‭ · 2021-08-28T13:34:41Z (over 3 years ago)
#6: Post deleted by user avatar General Sebast1an‭ · 2021-08-28T08:24:19Z (over 3 years ago)
#5: Post edited by user avatar Moshi‭ · 2021-08-28T01:25:39Z (over 3 years ago)
Focused the title
  • What's an equivalent implementation of this JavaScript program?
  • How do I filter an array in C?
No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing.

In [this challenge in Code Golf CD](https://codegolf.codidact.com/posts/283789), I have to make a program that computes the determinant of a two-dimensional array. It also has a program written in JavaScript that solves the challenge which looks like this:
```js
function laplaceDet(matrix) {
	if (matrix.length === 1) return matrix[0][0];

	let sum = 0;
	for (let rowIndex = 0; rowIndex < matrix.length; ++rowIndex) {
		let minorMatrix = matrix.filter((_, index) => index !== rowIndex)
			          .map(row => row.slice(1));
		sum += ((-1) ** rowIndex) * matrix[rowIndex][0] * laplaceDet(minorMatrix);
	}
	return sum;
}
```

I want to challenge myself into using C for solving the challenge. First, I'll need to reimplement the program, whereas the golfing part will be dealt with later, although I've already been golfing it. [Here's what I got so far.](https://tio.run/##HYvLCsMgEEXX@hUux0egWVu/JHQxhEwZG7SopYuSbzexcDmcxbnrtO6Ynr2zi56A9oxNGYOOU1NV/6RgghrCPFSUrX1KUrjcHte8FAflAp7v1bO1/ySGCy8b3vkL0@xYG1x41IYg6nGRR@8n)

Why'd I stop? There's a function named `filter()` and I'm not so sure how to get it implemented, and since C has no maps (at least I think none exist in C), it's also difficult to complete the program without it.

So I'll have to improvise... How? How do I implement the `filter()` method, maybe without using a function to save bytes, and what's a C equivalent to the line of code `matrix.filter((_, index) => index !== rowIndex).map(row => row.slice(1));`?
#4: Post edited by user avatar General Sebast1an‭ · 2021-08-28T01:15:48Z (over 3 years ago)
  • No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing.
  • In [this challenge in Code Golf CD](https://codegolf.codidact.com/posts/283789), I have to make a program that computes the determinant of a two-dimensional array. It also has a program written in JavaScript that solves the challenge which looks like this:
  • ```js
  • function laplaceDet(matrix) {
  • if (matrix.length === 1) return matrix[0][0];
  • let sum = 0;
  • for (let rowIndex = 0; rowIndex < matrix.length; ++rowIndex) {
  • let minorMatrix = matrix.filter((_, index) => index !== rowIndex)
  • .map(row => row.slice(1));
  • sum += ((-1) ** rowIndex) * matrix[rowIndex][0] * laplaceDet(minorMatrix);
  • }
  • return sum;
  • }
  • ```
  • I want to challenge myself into using C for solving the challenge. First, I'll need to reimplement the program, whereas the golfing part will be dealt with later, although I've already been golfing it. [Here's what I got so far.](https://tio.run/##S9ZNzknMS///P1MnSyfbOk0jLSc/sURBSytRJzOvRKFYs5qLMzNNo9jW1hDE5CxKLSktylNIjDaIBSJrLs7atPwiDetMm2LrTG1tsBKgGFft//8A)
  • Why'd I stop? There's a function named `filter()` and I'm not so sure how to get it implemented, and since C has no maps (at least I think none exist in C), it's also difficult to complete the program without it.
  • So I'll have to improvise... How? How do I implement the `filter()` method, maybe without using a function to save bytes, and what's a C equivalent to the line of code `matrix.filter((_, index) => index !== rowIndex).map(row => row.slice(1));`?
  • No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing.
  • In [this challenge in Code Golf CD](https://codegolf.codidact.com/posts/283789), I have to make a program that computes the determinant of a two-dimensional array. It also has a program written in JavaScript that solves the challenge which looks like this:
  • ```js
  • function laplaceDet(matrix) {
  • if (matrix.length === 1) return matrix[0][0];
  • let sum = 0;
  • for (let rowIndex = 0; rowIndex < matrix.length; ++rowIndex) {
  • let minorMatrix = matrix.filter((_, index) => index !== rowIndex)
  • .map(row => row.slice(1));
  • sum += ((-1) ** rowIndex) * matrix[rowIndex][0] * laplaceDet(minorMatrix);
  • }
  • return sum;
  • }
  • ```
  • I want to challenge myself into using C for solving the challenge. First, I'll need to reimplement the program, whereas the golfing part will be dealt with later, although I've already been golfing it. [Here's what I got so far.](https://tio.run/##HYvLCsMgEEXX@hUux0egWVu/JHQxhEwZG7SopYuSbzexcDmcxbnrtO6Ynr2zi56A9oxNGYOOU1NV/6RgghrCPFSUrX1KUrjcHte8FAflAp7v1bO1/ySGCy8b3vkL0@xYG1x41IYg6nGRR@8n)
  • Why'd I stop? There's a function named `filter()` and I'm not so sure how to get it implemented, and since C has no maps (at least I think none exist in C), it's also difficult to complete the program without it.
  • So I'll have to improvise... How? How do I implement the `filter()` method, maybe without using a function to save bytes, and what's a C equivalent to the line of code `matrix.filter((_, index) => index !== rowIndex).map(row => row.slice(1));`?
#3: Post edited by user avatar General Sebast1an‭ · 2021-08-28T01:10:14Z (over 3 years ago)
  • No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing.
  • In [this challenge in Code Golf CD](https://codegolf.codidact.com/posts/283789), I have to make a program that computes the determinant of a two-dimensional array. It also has a program written in JavaScript that solves the challenge which looks like this:
  • ```js
  • function laplaceDet(matrix) {
  • if (matrix.length === 1) return matrix[0][0];
  • let sum = 0;
  • for (let rowIndex = 0; rowIndex < matrix.length; ++rowIndex) {
  • let minorMatrix = matrix.filter((_, index) => index !== rowIndex)
  • .map(row => row.slice(1));
  • sum += ((-1) ** rowIndex) * matrix[rowIndex][0] * laplaceDet(minorMatrix);
  • }
  • return sum;
  • }
  • ```
  • I want to challenge myself into using C for solving the challenge. First, I'll need to reimplement the program, whereas the golfing part will be dealt with later, although I've already been golfing it. [Here's what I got so far.](https://tio.run/##S9ZNzknMS///P1MnSyfbOk0jUbOaizPLtjizKjUfxNOHsjLzSjS5ODPTNLJsbQ1BajiLUktKi/IUEqMNYoHImouzNi2/SMM60ybLOlNbG6wEKMZV@/8/AA "C (clang) – Try It Online")
  • Why'd I stop? There's a function named `filter()` and I'm not so sure how to get it implemented, and since C has no maps (at least I think none exist in C), it's also difficult to complete the program without it.
  • So I'll have to improvise... How? How do I implement the `filter()` method, maybe without using a function to save bytes, and what's a C equivalent to the line of code `matrix.filter((_, index) => index !== rowIndex).map(row => row.slice(1));`?
  • No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing.
  • In [this challenge in Code Golf CD](https://codegolf.codidact.com/posts/283789), I have to make a program that computes the determinant of a two-dimensional array. It also has a program written in JavaScript that solves the challenge which looks like this:
  • ```js
  • function laplaceDet(matrix) {
  • if (matrix.length === 1) return matrix[0][0];
  • let sum = 0;
  • for (let rowIndex = 0; rowIndex < matrix.length; ++rowIndex) {
  • let minorMatrix = matrix.filter((_, index) => index !== rowIndex)
  • .map(row => row.slice(1));
  • sum += ((-1) ** rowIndex) * matrix[rowIndex][0] * laplaceDet(minorMatrix);
  • }
  • return sum;
  • }
  • ```
  • I want to challenge myself into using C for solving the challenge. First, I'll need to reimplement the program, whereas the golfing part will be dealt with later, although I've already been golfing it. [Here's what I got so far.](https://tio.run/##S9ZNzknMS///P1MnSyfbOk0jLSc/sURBSytRJzOvRKFYs5qLMzNNo9jW1hDE5CxKLSktylNIjDaIBSJrLs7atPwiDetMm2LrTG1tsBKgGFft//8A)
  • Why'd I stop? There's a function named `filter()` and I'm not so sure how to get it implemented, and since C has no maps (at least I think none exist in C), it's also difficult to complete the program without it.
  • So I'll have to improvise... How? How do I implement the `filter()` method, maybe without using a function to save bytes, and what's a C equivalent to the line of code `matrix.filter((_, index) => index !== rowIndex).map(row => row.slice(1));`?
#2: Post edited by user avatar General Sebast1an‭ · 2021-08-27T22:42:25Z (over 3 years ago)
  • No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing.
  • In [this challenge in Code Golf CD](https://codegolf.codidact.com/posts/283789), I have to make a program that computes the determinant of a two-dimensional array. It also has a program written in JavaScript that solves the challenge which looks like this:
  • ```js
  • function laplaceDet(matrix) {
  • if (matrix.length === 1) return matrix[0][0];
  • let sum = 0;
  • for (let rowIndex = 0; rowIndex < matrix.length; ++rowIndex) {
  • let minorMatrix = matrix.filter((_, index) => index !== rowIndex)
  • .map(row => row.slice(1));
  • sum += ((-1) ** rowIndex) * matrix[rowIndex][0] * laplaceDet(minorMatrix);
  • }
  • return sum;
  • }
  • ```
  • I want to challenge myself into using C for solving the challenge. First, I'll need to reimplement the program, whereas the golfing part will be dealt with later, although I've already been golfing it. [Here's what I got so far.](https://tio.run/##S9ZNzknMS///P1MnSyfbOk0jUbOaizPLtjizKjUfxNOHsjLzSjS5ODPTNLJsbQ1BajiLUktKi/IUEqMNYoHImouzNi2/SMM60ybLOlNbG6wEKMZV@/8/AA "C (clang) – Try It Online")
  • <div style="color:red">Why'd I stop?</div> There's a function named `filter()` and I'm not so sure how to get it implemented, and since C has no maps (at least I think none exist in C), it's also difficult to complete the program without it.
  • So I'll have to improvise... How? How do I implement the `filter()` method, maybe without using a function to save bytes, and what's a C equivalent to the line of code `matrix.filter((_, index) => index !== rowIndex).map(row => row.slice(1));`?
  • No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing.
  • In [this challenge in Code Golf CD](https://codegolf.codidact.com/posts/283789), I have to make a program that computes the determinant of a two-dimensional array. It also has a program written in JavaScript that solves the challenge which looks like this:
  • ```js
  • function laplaceDet(matrix) {
  • if (matrix.length === 1) return matrix[0][0];
  • let sum = 0;
  • for (let rowIndex = 0; rowIndex < matrix.length; ++rowIndex) {
  • let minorMatrix = matrix.filter((_, index) => index !== rowIndex)
  • .map(row => row.slice(1));
  • sum += ((-1) ** rowIndex) * matrix[rowIndex][0] * laplaceDet(minorMatrix);
  • }
  • return sum;
  • }
  • ```
  • I want to challenge myself into using C for solving the challenge. First, I'll need to reimplement the program, whereas the golfing part will be dealt with later, although I've already been golfing it. [Here's what I got so far.](https://tio.run/##S9ZNzknMS///P1MnSyfbOk0jUbOaizPLtjizKjUfxNOHsjLzSjS5ODPTNLJsbQ1BajiLUktKi/IUEqMNYoHImouzNi2/SMM60ybLOlNbG6wEKMZV@/8/AA "C (clang) – Try It Online")
  • Why'd I stop? There's a function named `filter()` and I'm not so sure how to get it implemented, and since C has no maps (at least I think none exist in C), it's also difficult to complete the program without it.
  • So I'll have to improvise... How? How do I implement the `filter()` method, maybe without using a function to save bytes, and what's a C equivalent to the line of code `matrix.filter((_, index) => index !== rowIndex).map(row => row.slice(1));`?
#1: Initial revision by user avatar General Sebast1an‭ · 2021-08-27T22:41:52Z (over 3 years ago)
What's an equivalent implementation of this JavaScript program?
No, I'm not trying to get the full program written completely in C by you guys. I only need some way to implement the functionalities of each function I found confusing.

In [this challenge in Code Golf CD](https://codegolf.codidact.com/posts/283789), I have to make a program that computes the determinant of a two-dimensional array. It also has a program written in JavaScript that solves the challenge which looks like this:
```js
function laplaceDet(matrix) {
	if (matrix.length === 1) return matrix[0][0];

	let sum = 0;
	for (let rowIndex = 0; rowIndex < matrix.length; ++rowIndex) {
		let minorMatrix = matrix.filter((_, index) => index !== rowIndex)
			          .map(row => row.slice(1));
		sum += ((-1) ** rowIndex) * matrix[rowIndex][0] * laplaceDet(minorMatrix);
	}
	return sum;
}
```

I want to challenge myself into using C for solving the challenge. First, I'll need to reimplement the program, whereas the golfing part will be dealt with later, although I've already been golfing it. [Here's what I got so far.](https://tio.run/##S9ZNzknMS///P1MnSyfbOk0jUbOaizPLtjizKjUfxNOHsjLzSjS5ODPTNLJsbQ1BajiLUktKi/IUEqMNYoHImouzNi2/SMM60ybLOlNbG6wEKMZV@/8/AA "C (clang) – Try It Online")

<div style="color:red">Why'd I stop?</div> There's a function named `filter()` and I'm not so sure how to get it implemented, and since C has no maps (at least I think none exist in C), it's also difficult to complete the program without it.

So I'll have to improvise... How? How do I implement the `filter()` method, maybe without using a function to save bytes, and what's a C equivalent to the line of code `matrix.filter((_, index) => index !== rowIndex).map(row => row.slice(1));`?