c - 从文件加载数组

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我正在使用fwrite保存数组的元素我正在尝试使用 fread 将以前保存的数据加载到数组中。返回值fread非零，这意味着它是成功的。但是当我打印数组时，它是空的，没有任何内容被打印。我已将数组保存到文件中

fwrite(num, sizeof(int), k, q); //num is the same array, k=no of elements, q is the file pointer

这是我的代码:

int num[50], NoOfElement;
FILE *p;
if(p = fopen("data.txt", "rb") == NULL)
{
    printf("Error");
    exit(1);
}
fseek(p, 0, SEEK_END);
NoOfElement = ftell(p) / sizeof(int); //no of elements in the file
fseek(p, 0, SEEK_SET);
fread(num, sizeof(int), NoOfElement, p);

Answer 1

你的代码看起来不错。这个演示程序对我来说工作正常:

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

int main()
{
    int num[50], NoOfElement;
    FILE *P;
    int i;

    // Generate test data
    for (i = 0; i < 5; ++i)
        num[i] = i+1;

    // Write test data
    P = fopen("data.txt", "wb");
    fwrite(num, sizeof(int), 5, P);
    fclose(P);

    // Overwrite the test data so we know we read it OK
    for (i = 0; i < 5; ++i)
        num[i] = -1;

    // Your code for reading test data
    if((P = fopen("data.txt", "rb")) == NULL)
    {
        printf("Error");
        exit(1);
    }
    fseek(P, 0, SEEK_END);
    NoOfElement = ftell(P) / sizeof(int); //no of elements in the file
    fseek(P, 0, SEEK_SET);
    fread(num, sizeof(int), NoOfElement, P);

    // Output test data (shows 1 -> 5 as expected)
    for (i = 0; i < NoOfElement; ++i)
        printf("%d\n", num[i]);
}