Question

所以我花了几个小时试图找出为什么我的realloc没有扩大我的结构数组，但我似乎没有取得任何进展。 Realloc要么失败，要么放大阵列。我做的是否有任何明显的错误？

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


typedef struct fileInfo {
    char accessRights[12];
    short hardLinks;
    short userName;
    short groupName;
    long size;
    char *time;
    char *fileName;
    short nrOfNode;
} fileInfo;


void enlargeFileInfos(fileInfo *fileInfoArray, int currentSize)
{
    fileInfo *temp = (fileInfo*)realloc(fileInfoArray, (currentSize + 1) * sizeof(fileInfo));
    if (!temp) {
        printf("realloc --FAILED--\n");
        return;
    }
    fileInfoArray = temp;
    printf("fileInfo grew to %d item(s)\n", currentSize + 1);
}

int main( )
{
    size_t nrOfDirs = 1;
    fileInfo *fileInfoArr = malloc(sizeof(fileInfo));

    for (int i = 0; i < 5; i++) {
        enlargeFileInfos(fileInfoArr, nrOfDirs);
        nrOfDirs++;
    }
    return 0;
}

Answer 1

要realloc指向fileInfoArray内的enlargeFileInfos内存，您必须将其地址传递给该函数：

void enlargeFileInfos(fileInfo **fileInfoArray, int currentSize)
{
    fileInfo *temp = realloc(*fileInfoArray, (currentSize + 1) * sizeof(fileInfo));
    if (temp == NULL) {
        printf("realloc --FAILED--\n");
        return;
    }
    *fileInfoArray = temp;
    printf("fileInfo grew to %d item(s)\n", currentSize + 1);
}

然后以这种方式调用函数：

enlargeFileInfos(&fileInfoArr, nrOfDirs);

正如评论中 Jonathan Leffler 所指出的，另一种方法是从函数realloc返回enlargeFileInfos ed内存：

fileInfo *enlargeFileInfos(fileInfo *fileInfoArray, int currentSize)
{
    fileInfo *temp = realloc(fileInfoArray, (currentSize + 1) * sizeof(fileInfo));
    if (temp == NULL) {
        printf("realloc --FAILED--\n");
        return NULL;
    }
    printf("fileInfo grew to %d item(s)\n", currentSize + 1);
    return temp;
}

而且，你用这种方式：

fileInfoArr = enlargeFileInfos(fileInfoArr, nrOfDirs);
if (fileInfoArr == NULL) {
    /* Handle allocation failure */    
}

使用fileInfoArr后，请不要忘记释放它：

free(fileInfoArr);

我已从realloc移除了演员，因此请查看Do I cast the result of malloc?，并将main的签名更改为int main(void)。

重新分配结构数组

1 个答案: