sort.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

struct _element {
    char icao_code[5];
    char station_name[100];
};

typedef struct _element element;

void insertion_sort(element* stations, int size) {
    int i, j;
    element tmp;

    for(j = 2; j < size; j++) {
        tmp = stations[j];

        i = j - 1;

        while(i >= 0 && strcmp(stations[i].icao_code, tmp.icao_code) > 0) {
            stations[i+1] = stations[i];
            i--;
        }

        stations[i+1] = tmp;

    }
}

void selection_sort(element* stations, int size) {
    int j, i, smallestIndex;
    element tmp;

    for(j = 0; j <= size - 1; j++) {
        smallestIndex = j;

        // find remaining smallest element
        for(i = j + 1; i < size; i++) {
            if (strcmp(stations[i].icao_code, stations[smallestIndex].icao_code) < 0) {
                smallestIndex = i;
            }
        }

        tmp = stations[smallestIndex];
        stations[smallestIndex] = stations[j];
        stations[j] = tmp;
    }
}

int quick_sort_partition(element * stations, int left, int right, char * x) {
    int i, j;
    element tmp;

    i = left - 1;
    j = right;

    while (i <= j) {
        while(strcmp(stations[i].icao_code, x) < 0) {
            i++;
        }

        while(strcmp(stations[j].icao_code, x) > 0) {
            j--;
        };

        if (i <= j) {
            tmp = stations[i];
            stations[i] = stations[j];
            stations[j] = tmp;
        }
    }

    tmp = stations[i];
    stations[i] = stations[right];
    stations[right] = tmp;

    return i;
}

void quick_sort(element* stations, int left, int right) {
    if (left < right) {
        int i, j;
        element pivot, temp;

        pivot = stations[left];

        i = left;
        j = right + 1;

        while (1) {
            do i++; while (i <= right && strcmp(stations[i].icao_code, pivot.icao_code) <= 0);
            do j--; while (strcmp(stations[j].icao_code, pivot.icao_code) > 0);
            if (i >= j) break;
            temp = stations[i];
            stations[i] = stations[j];
            stations[j] = temp;
        }

        temp = stations[left];
        stations[left] = stations[j];
        stations[j] = temp;

        quick_sort(stations, left, j-1);
        quick_sort(stations, j+1, right);
    }
}

void merge_sort(element* stations, element* tmpStations, int left, int right) {
    if (left < right) {
        // divide
        int middle;
        middle = (left + right) / 2;
        merge_sort(stations, tmpStations, left, middle);
        merge_sort(stations, tmpStations, middle + 1, right);

        // merge
        int i, j, k;

        i = left;
        j = right;
        k = left;

        while (i <= middle)
            tmpStations[k++] = stations[i++];

        while (j > middle)
            tmpStations[k++] = stations[j--];

        i = left;
        j = right;
        k=left;

        while (i <= j) {
            if (strcmp(tmpStations[i].icao_code, tmpStations[j].icao_code) <= 0) {
                stations[k++] = tmpStations[i++];
            } else {
                stations[k++] = tmpStations[j--];
            }
        }
    }
}



void print_stations(element* stations, int size) {
    int i;
    for (i = 0; i < size; i++) {
        printf("%s : %s", stations[i].icao_code, stations[i].station_name);
    }
}

int readfile(element* stations, int* size) {
    FILE * fp;
    char line[100]; // keeps one line of the file

    // try to open the file; in case of an error exit the program
    *size = 0;
    fp = fopen("stations.csv", "r");
    if (!fp) {
        printf("Cannot open file stations.csv!\n");
        return 1;
    }

    // read all weather stations from file and add them to the
    // hash table
    while (!feof(fp)) {
        // read one line and skip empty and comment lines
        fgets(line, 100, fp);
        if (line[0] == '#') continue;
        if (isspace(line[0])) continue;

        // take the first 4 characters as key value
        strncpy(stations[*size].icao_code, line, 4);
        stations[*size].icao_code[4] = '\0';

        // take the rest as value
        strcpy(stations[*size].station_name, strchr(line, ';')+1);
        *size += 1;
    }

    // close the file
    fclose(fp);

    return 0;
}

int main(int argc, char** argv) {
    element* stations; // holds the station codes and names
    element* tmpStations; // holds temporary station codes and names for merge sort
    int size; // holds the number of valid entries in the array

    stations = (element*)malloc(sizeof(element)*6000);
    tmpStations = (element*)malloc(sizeof(element)*6000);

    // now lets try insertion sort
    printf("Sorting with insertion sort:\n\n");
    // read the station data from file
    readfile(stations, &size);
    // sort the station names
    insertion_sort(stations, size);
    // print the result
    print_stations(stations, size);

    // now lets try selection sort
    printf("Sorting with selection sort:\n\n");
    // read the station data from file
    readfile(stations, &size);
    // sort the station names
    selection_sort(stations, size);
    // print the result
    print_stations(stations, size);

    // now lets try merge sort
    printf("Sorting with merge sort:\n\n");
    // read the station data from file
    readfile(stations, &size);
    // sort the station names
    merge_sort(stations, tmpStations, 0, size-1);
    // print the result
    print_stations(stations, size);

    // now lets try quick sort
    printf("Sorting with quick sort:\n\n");
    // read the station data from file
    readfile(stations, &size);
    // sort the station names
    quick_sort(stations, 0, size-1);
    // print the result
    print_stations(stations, size);

    free(stations);
    free(tmpStations);
    
    return 0;
}

can u share the csv file ?