85. Linear Search in Array

#include <stdio.h>
#include <stdint.h>

// Perform linear search in array
int linear_search(uint8_t *arr, uint8_t n, uint8_t key) {
    for (uint8_t i = 0; i < n; i++) {
        if (arr[i] == key) {
            return i;  // Found key, return index
        }
    }
    return -1;  // Not found
}

int main() {
    uint8_t n, key;
    scanf("%hhu", &n);
    uint8_t arr[100];

    for (uint8_t i = 0; i < n; i++) {
        scanf("%hhu", &arr[i]);
    }
    scanf("%hhu", &key);

    int index = linear_search(arr, n, key);
    printf("%d", index);
    return 0;
}

What’s the goal?

Scan the array one-by-one to find the first matching value of the key. Return its index.

Why it matters in firmware?

• Used to search device IDs, sensor lookup tables, ADC conversion zones
• Faster to implement in small tables without extra memory
• Avoids binary search when sorting is not guaranteed

Solution Logic

• Loop from index 0 to n-1
• Compare each element with the key
• Return index when matched
• If loop completes, return -1 (not found)