calloc وrealloc

ما بعد malloc

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

int main(void) {
    int *p = calloc(3, sizeof(int));
    printf("%d %d %d\n", p[0], p[1], p[2]);
    free(p);
    return 0;
}

‏calloc يصفّر الذاكرة

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

int main(void) {
    int *a = calloc(5, sizeof(int));
    int sum = 0;
    for (int i = 0; i < 5; i++) sum += a[i];
    printf("sum of zeroed array = %d\n", sum);
    free(a);
    return 0;
}

‏calloc له وسيطان

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

int main(void) {
    double *d = calloc(4, sizeof(double));
    d[2] = 1.5;
    printf("%f %f\n", d[0], d[2]);
    free(d);
    return 0;
}

‏malloc مقابل calloc

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

int main(void) {
    int *m = malloc(2 * sizeof(int));
    int *c = calloc(2, sizeof(int));
    m[0] = 5; m[1] = 6;
    printf("malloc: %d %d\n", m[0], m[1]);
    printf("calloc: %d %d\n", c[0], c[1]);
    free(m); free(c);
    return 0;
}

التوسيع باستخدام realloc

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

int main(void) {
    int *a = malloc(2 * sizeof(int));
    a[0] = 1; a[1] = 2;
    a = realloc(a, 4 * sizeof(int));
    a[2] = 3; a[3] = 4;
    for (int i = 0; i < 4; i++) printf("%d ", a[i]);
    printf("\n");
    free(a);
    return 0;
}

قد تنقل realloc الكتلة

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

int main(void) {
    int *a = malloc(sizeof(int));
    a[0] = 42;
    int *bigger = realloc(a, 100 * sizeof(int));
    printf("first element still %d\n", bigger[0]);
    free(bigger);
    return 0;
}

نمط realloc الآمن

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

int main(void) {
    int *a = malloc(2 * sizeof(int));
    int *tmp = realloc(a, 8 * sizeof(int));
    if (tmp == NULL) {
        free(a);
        return 1;
    }
    a = tmp;
    a[7] = 99;
    printf("%d\n", a[7]);
    free(a);
    return 0;
}

تقليص كتلة

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

int main(void) {
    int *a = malloc(6 * sizeof(int));
    for (int i = 0; i < 6; i++) a[i] = i;
    a = realloc(a, 3 * sizeof(int));
    printf("%d %d %d\n", a[0], a[1], a[2]);
    free(a);
    return 0;
}

مخزن متنامٍ

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

int main(void) {
    int cap = 2, len = 0;
    int *a = malloc(cap * sizeof(int));
    for (int v = 0; v < 5; v++) {
        if (len == cap) {
            cap *= 2;
            a = realloc(a, cap * sizeof(int));
        }
        a[len++] = v;
    }
    printf("len=%d cap=%d last=%d\n", len, cap, a[len-1]);
    free(a);
    return 0;
}

‏realloc مع NULL

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

int main(void) {
    int *a = realloc(NULL, 3 * sizeof(int));
    a[0] = 7;
    printf("%d\n", a[0]);
    free(a);
    return 0;
}

دمجها معًا

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

int main(void) {
    int *a = calloc(2, sizeof(int));
    a = realloc(a, 4 * sizeof(int));
    a[2] = 0; a[3] = 0;
    printf("%d %d %d %d\n", a[0], a[1], a[2], a[3]);
    free(a);
    return 0;
}

تحقّق سريع

مراجعة