写作结构的数组在C二进制文件 [英] Writing an array of structs to a binary file in C

问题描述

我有结构的数组，我想写到一个二进制文件。我有一个为write.c程序和read.c程序。该方案为write.c似乎能正常工作，但是当我运行该程序read.c我得到一个分段错误。我是新的C所以这将是巨大的，如果有人能看在我的code任何明显的错误。我保证这不是太长：）

为write.c：

 的#include＆LT;＆stdlib.h中GT;
＃包括LT＆;＆stdio.h中GT;结构人
{
    烧焦f_name [256];
    焦炭l_name [256];
    INT年龄;
};INT主（INT ARGC，CHAR *的argv []）
{
    结构*人的人;
    INT PEOPLE_COUNT;    的printf（有多少人你想创造：）;
    scanf函数（％i的，＆安培; PEOPLE_COUNT）;
    人=的malloc（sizeof的（结构人）* PEOPLE_COUNT）;    INT N;
    为（N = 0; N＆LT; PEOPLE_COUNT; N ++）
    {
        的printf（％的人我的名字：N）;
        scanf函数（％S，人[N] .f_name）;        的printf（％的人我的姓氏，N）;
        scanf函数（％S，人[N] .l_name）;        的printf（％的人我的年龄：，N）;
        scanf函数（％i的，＆安培;人[N]。年龄）;
    }    FILE *的数据;
    如果（（数据= FOPEN（data.bin，世行））== NULL）
    {
        的printf（打开文件时出错\\ n）;
        返回1;
    }    FWRITE（人的sizeof（结构人）* PEOPLE_COUNT，1，数据）;
    FCLOSE（数据）;    返回0;
}
 

read.c：

 的#include＆LT;＆stdlib.h中GT;
＃包括LT＆;＆stdio.h中GT;结构人
{
    烧焦f_name [256];
    焦炭l_name [256];
    INT年龄;
};INT主（INT ARGC，CHAR *的argv []）
{
    FILE *的数据;
    如果（（数据= FOPEN（data.bin，RB））== NULL）
    {
        的printf（打开文件时出错\\ n）;
        返回1;
    }    结构*人的人;    FREAD（人的sizeof（结构人）* 1 / *刚看了一人* / 1，数据）;
    的printf（％S \\ n，让人[0] .f_name）;    FCLOSE（数据）;    返回0;
}
 

感谢您的帮助！

解决方案

 结构人*人;
 

这只是分配一个指针结构，但你没有实际结构内容有任何分配的空间。要么使用的malloc 同样你写的程序，或尝试这样的：

 结构的人的人;
FREAD（安培;人的sizeof（人），1，数据）;
 

I have an array of structs I would like to write to a binary file. I have a write.c program and a read.c program. The write.c program seems to be working properly but when I run the read.c program I get a segmentation fault. I'm new to C so It would be great if someone could look over my code for any obvious errors. I promise it's not too long :)

write.c:

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

struct Person 
{
    char f_name[256];
    char l_name[256];
    int age;
};

int main(int argc, char* argv[])
{
    struct Person* people;
    int people_count;

    printf("How many people would you like to create: ");
    scanf("%i", &people_count);
    people = malloc(sizeof(struct Person) * people_count);  

    int n;
    for (n = 0; n < people_count; n++)
    {
        printf("Person %i's First Name: ", n);
        scanf("%s", people[n].f_name);

        printf("Person %i's Last Name: ", n);
        scanf("%s", people[n].l_name);

        printf("Person %i's Age: ", n);
        scanf("%i", &people[n].age);
    }

    FILE* data;
    if ( (data = fopen("data.bin", "wb")) == NULL )
    {
        printf("Error opening file\n");
        return 1;   
    }

    fwrite(people, sizeof(struct Person) * people_count, 1, data);
    fclose(data);

    return 0;
}

read.c:

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

struct Person 
{
    char f_name[256];
    char l_name[256];
    int age;
};

int main(int argc, char* argv[])
{
    FILE* data;
    if ((data = fopen("data.bin", "rb")) == NULL)
    {
        printf("Error opening file\n");
        return 1;
    }

    struct Person* people;

    fread(people, sizeof(struct Person) * 1/* Just read one person */, 1, data);
    printf("%s\n", people[0].f_name);

    fclose(data);

    return 0;
}

Thanks for the help!

解决方案

struct Person* people;

This allocates just a pointer to struct, but you don't have any allocated space for actual struct contents. Either use malloc similarly to your write program, or try something like:

struct Person people;
fread(&people, sizeof(people), 1, data);

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