3

我想知道如何将包含 int 数组的结构分配给结构数组。无论我想到什么新的解决方案，我都会得到不正确的结果。

我相信问题在于这段代码：

struct Codes *create(int as) {
    struct Codes *c = malloc(sizeof (struct Codes)+as * sizeof (int));
    c->as = as;
    for (int i = 0; i < as; i++) {
        c->a[i] = i;
    }

    return c;
}

整个代码：

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

struct Codes {
    int as;
    int a[];
};

struct Code {
    int as;
    struct Codes *ci[];
};

struct Codes *create(int as) {
    struct Codes *c = malloc(sizeof (struct Codes)+as * sizeof (int));
    c->as = as;
    for (int i = 0; i < as; i++) {
        c->a[i] = i;
    }

    return c;
}

struct Code *and(int as, struct Codes *cd) {
    struct Code *c = malloc(sizeof (struct Code)+as * sizeof (struct Codes));
     for (int i = 0; i < as; i++) {
        c->ci[i] = cd;
    }
    c->as = as;
    return c;
}

int main(int argc, char **argv) {

    struct Codes *cd;
    cd = create(4);

    struct Code *c;
    c = and(2, cd);

    for (int i = 0; i < c->as; i += 1) {
        for (int j=0; j < c->ci[i]->as; j++) {
            printf("%d \n", c->ci[i]->a[j]);
       }
    }

    free(cd);
    free(c);

}//main

实际结果：

0 
1 
2 
3

预期结果：

0 
1 
2 
3
0
1
2
3
4

1 回答 1

1

struct Code *c = malloc(sizeof (struct Code)+as * sizeof (struct Codes));是不正确的。struct Code 的 ci 是一个指针数组，但是您为结构数组分配了空间。

要解决此问题，请更改为sizeof(struct Codes *)，或者最好使用取消引用指向您为其分配空间的类型的指针的模式：

struct Code *c = malloc( sizeof *c + as * sizeof c->ci[0] );

Also, for (int j; should be for (int j = 0; . Your code causes undefined behaviour by using uninitialized value of j, it's just chance that you happened to get the output you did. Using the gcc flag -Wextra would have diagnosed this error.

于 2016-10-05T03:39:48.580 回答