構造体の動的配列 (realloc)

明解Ｃ言語入門編 > 12. 構造体 >

C



#include <stdio.h>

#include <string.h>

#include <alloc.h>
#define NINSU 5
typedef struct

{

    char  name[20];

    int   height;

    float weight;

} gstudent;
typedef

    int (*compare)(gstudent*, gstudent*);
int compare_height(gstudent* x, gstudent* y)

{

    if (x->height > y->height) return  1;

    if (x->height < y->height) return -1;

    return 0;

}

int compare_weight(gstudent* x, gstudent* y)

{

    if (x->weight > y->weight) return  1;

    if (x->weight < y->weight) return -1;

    return 0;

}
void swap(gstudent* x, gstudent* y)

{

    gstudent tmp = *x;

    *x = *y;

    *y = tmp;

}
void sort(gstudent data[], int n, compare comp)

{

    int k = n - 1;

    while (k >= 0)

    {

        int i, j;

        for (i = 1, j = -1; i <= k; i++)

        {

            if (comp(&data[i - 1], &data[i]) > 0)

            {

                j = i - 1;

                swap(&data[i], &data[j]);

            }

        }

        k = j;

    }

}
void set_student(gstudent* std, char name[], int height, float weight)

{

    strcpy(std->name, name);

    std->height = height;

    std->weight = weight;

}
int main(int argc, char* argv[])

{

    int i;

    gstudent* data;

    data = (gstudent*)malloc(sizeof(gstudent) * 3);
    set_student(&data[0], "Sato",    178, 61.0);

    set_student(&data[1], "Sanaka",  175, 60.5);

    set_student(&data[2], "Takao",   173, 80.0);
    data = (gstudent*)realloc(data, sizeof(gstudent) * 5);

    set_student(&data[3], "Mike",    165, 72.0);

    set_student(&data[4], "Masaki",  179, 77.5);
    puts("ソート前：");

    for (i = 0; i < NINSU; i++)

        printf("%2d:%-8s%4d%6.1f\n", i + 1, data[i].name, data[i].height, data[i].weight);

    puts("");
    /* 身長でソート */

    sort(data, NINSU, &compare_height);
    puts("身長でソート後：");

    for (i = 0; i < NINSU; i++)

        printf("%2d:%-8s%4d%6.1f\n", i + 1, data[i].name, data[i].height, data[i].weight);

    puts("");
    /* 体重でソート */

    sort(data, NINSU, &compare_weight);
    puts("体重でソート後：");

    for (i = 0; i < NINSU; i++)

        printf("%2d:%-8s%4d%6.1f\n", i + 1, data[i].name, data[i].height, data[i].weight);
    free(data);
    return 0;

}

実行結果

T:\>lesson099\project1.exe
ソート前：
1:Sato 178 61.0
2:Sanaka 175 60.5
3:Takao 173 80.0
4:Mike 165 72.0
5:Masaki 179 77.5

身長でソート後：
1:Mike 165 72.0
2:Takao 173 80.0
3:Sanaka 175 60.5
4:Sato 178 61.0
5:Masaki 179 77.5

体重でソート後：
1:Sanaka 175 60.5
2:Sato 178 61.0
3:Mike 165 72.0
4:Masaki 179 77.5
5:Takao 173 80.0