c - 如何从指针获取正确的输入值

Question

这个问题已经有答案了:

How to find the size of an array (from a pointer pointing to the first element array)? (17 个回答)

已关闭 8 年前。

我想使用一个函数来接收指向数组的指针及其大小，并将所有元素值设置为零。

但是在函数中检查了数组的值，该值不是1234，如果正确的话应该是1234，因为输入值是1234。

只是想知道我的以下代码中的错误在哪里。

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

void receive(int *point, const int size);

int main(void) {
    int a;
    int *b;
    scanf("%d", &a);
    b=(int*)malloc(sizeof(int)*a);

    printf("size of input: %d\n", sizeof(b));
    receive(b, sizeof(b));
    free(b);
    return 0;
}

void receive(int *point, const int size) {
    int c=sizeof(*point);

    printf("filling the array to zero");
    int i;
    for (i=0; i<c; i++) {
        printf("\n previous_value:%d\n", point[i]);
        point[i]=0;
        printf(", current_value %d\n", point[i]);
    }
}

Answer 1

我改了一些不正确的语句，结果代码是:

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

void receive(int *point, const int size);

int main(void) {
    int a;
    int *b;
    scanf("%d", &a);
    b= malloc(sizeof(int)*a); //removed implicit declaration of malloc return value

    printf("size of input: %d\n", a);
    receive(b, a); //changed sizeof(b) to a as second argument of function
    free(b);
    return 0;
}

void receive(int *point, const int size) {

    //removed int c = sizeof(*point); unnecessary statement
    printf("filling the array to zero");
    int i;
    for (i=0; i<size; i++) {              //substituted c with size
        printf("\n previous_value:%d\n", point[i]);
        point[i]=0;
        printf(", current_value %d\n", point[i]);
    }
}