ft_range — Integer Array from Range

Allowed functions: malloc

It must allocate (with malloc()) an array of integers, fill it with consecutive values that begin at start and end at end (including start and end!), then return a pointer to the first value of the array.

int     *ft_range(int start, int end);

Examples

• With (1, 3) you will return an array containing 1, 2 and 3.
• With (-1, 2) you will return an array containing -1, 0, 1 and 2.
• With (0, 0) you will return an array containing 0.
• With (0, -3) you will return an array containing 0, -1, -2 and -3.

Solution

Download ft_range.c

#include <stdlib.h>

int *ft_range(int start, int end) {
	int step;
	int len = 0;
	int *arr;
	if (start <= end) {

		len = end - start + 1;
		step = 1;
	}

	else {
		len = start - end + 1;
		step = -1;
	}

	arr = malloc(sizeof(int) * len);
	if (!arr) {
		return (NULL);
	}
	int i = 0;

	while (i < len) {
		arr[i] = start + (i * step);
		i++;
	}
	return arr;
}

How It Works

Goal: Allocate and return an array of consecutive integers from start to end.

Approach: Determine the array length and step direction, allocate memory, then fill the array using the step.

Step by step:

1. Compare start and end to calculate the array length and set step to 1 (ascending) or -1 (descending).
2. Allocate an integer array of the computed length with malloc.
3. Fill the array by setting arr[i] = start + (i * step), which produces consecutive values in the correct direction.

Key concept: Dynamic memory allocation with malloc and handling both ascending and descending ranges using a step variable.