Binary files read & write

Question

So I have a problem with binary file.(Yea i'm a beginner, but I know some things.)

Why does my binary file not "remember" what I wrote last time I run my program?

It's like it just deletes everything or just can't read what's inside file, so every time I run my program I need to write all parameteres again.

Header.h

using (StreamReader sr = new StreamReader(File.OpenRead(s)))
{
    textToReturn = sr.ReadToEnd();
}

This is inside main(Source.c)

Thread.Sleep(2500)

This is inside function, also functions are organized in different file(Functions.c).

#ifndef HEADER_H
#define HEADER_H

typedef struct user {
    char name[30];
    char last_name[30];
    int id_number;
    int phone;
} USER;

void reading(FILE*, int, USER*);
void writeing(FILE*, int, USER*);


#endif

Answer 1

您不会在文件中写入任何内容，至少不会在您提供的代码段中写入任何内容。您可能想要做的是：

// my guess what USER is, because you didn't provide.....
typedef struct USER_s {
char name[200];
char last_name[200];
int id_number;
int phone;
} USER;

void writeing(FILE* dat, int user_number, USER* user) {

    int i = user_number- 1;

    printf("Name: ");
    scanf("%s", (user + i)->name);

    printf("Last name: ");
    scanf("%s", (user + i)->last_name);

    printf("ID number: ");
    scanf("%d", &(user + i)->id_number);

    printf("Phone: ");
    scanf("%d", &(user + i)->phone);

    // write 1 time sizeof(USER) length data pointed to by 'user' variable to dat file
    size_t ret = fwrite(&user[i], sizeof(*user), 1, dat);
    // assertion for safety
    assert(ret == sizeof(*user));
}

void ispis(FILE* dat, int user_number, USER* user)
{
    // read from dat file user_number times sizeof(USER) length data and save to user array
    // user pointer can handle sizeof(USER)*user_number bytes
    size_t ret = fread(user, sizeof(USER), user_number, dat);
    // assertion for safety
    assert(ret == sizeof(USER)*user_number);

    for (int i = 0; i < user_number; i++)
    {
        fprintf(stdout, "Name: %s\nLast name: %s\nID number: %d\nPhone: 0%d\n", (user + i)->name, (user + i)->last_name, (user + i)->id_number, (user + i)->phone);
    }
}

顺便说一下。您可能会感兴趣，(user + i)->name与user[i].name相同。