reading from structs in a binary file

Hi, I created a program that takes in input from the user and stores it in a struct and then takes that struct and stores it into a binary file. Now what I'd like to do is read a particular piece of information from those records, like the of age of a person, so that I can compare it to the ages within other records. How would I go about taking out those particular bits of info?

Say I have a this struct erecc[x].age stored in that binary, how would I get it out?

You could read a whole struct from file into a temporary struct in one go and then access the value through the temporary struct.

How would I go about doing that? I see where you're going with this but I'm unfamiliar with the commands.

Something like -

struct something s;
fread(&s,sizeof(struct something),1,fileptr);

then you'd access elements of the struct normally.

Example:

Code:

---

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

#define DATA_FILE  "data~.txt"

struct DataRec
{
        char Name[31];
        unsigned int Age;
};

static void WriteData();
static void ReadData();

int main(int argc, char* argv[])
{
        /* CREATE SOME TEST DATA */
        WriteData();

        /* READ THE TEST DATA BACK FROM THE FILE */
        ReadData();

        return 0;
}

static void
WriteData()
{
        FILE *fp;
        struct DataRec MyRec;

        if ((fp = fopen(DATA_FILE, "w")) != NULL)
        {
                strcpy(MyRec.Name, "John Public");
                MyRec.Age = 25;

                fwrite(&MyRec, sizeof(MyRec), 1, fp);

                strcpy(MyRec.Name, "Mike Miller");
                MyRec.Age = 30;

                fwrite(&MyRec, sizeof(MyRec), 1, fp);

                fclose(fp);
        }
}

static void
ReadData()
{
        FILE *fp;
        struct DataRec Rec1;
        struct DataRec Rec2;

        if ((fp = fopen(DATA_FILE, "r")) != NULL)
        {
                /* read the first structure but don't display it */
                fread(&Rec1, sizeof(DataRec), 1, fp);
               
                /* read the second structure and display it */
                fread(&Rec2, sizeof(DataRec), 1, fp);

                printf("Name: %s  Age: %d\n", Rec1.Name, Rec1.Age);
                printf("Name: %s  Age: %d\n", Rec2.Name, Rec2.Age);

                if (Rec1.Age == Rec2.Age)
                        printf("Ages are the same\n");
                else
                        printf("Ages are different\n");
               

                fclose(fp);
        }
}

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