Question

How to find the longest common string prefix in array of strings in C

Answer 1

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
   
#define ROWS 3
#define COLS 20

int compare_function(const void *a, const void *b) {
  return strcmp(a, b);
}

int min_length(char arr[][COLS]) {
    int min = strlen(arr[0]);

    for (int i = 1; i < ROWS; i++) {
        int size = strlen(arr[i]);
        if (size < min) min = size;
    }
    
    return min;
}

int main() {
    char arr[ROWS][COLS] = {"cartography", "carburettor", "carbonating"}; 
    
    qsort(arr, (size_t)ROWS, COLS, compare_function);
    
    int m_length = min_length(arr);

    int i = 0;
    while (i < m_length && arr[0][i] == arr[ROWS - 1][i]) 
        i++; 

    printf("Longest common prefix: %.*s\n", i, arr[0]);

    return 0;
}




/*
run:

Longest common prefix: car

*/

 

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