File reading and writing C

Question

I have a problem reading and writing to a file. I use fwrite and write a amount of struct arrays. After that I write to the file if there isn't one.

If there is on the first byte of the file is how many winners who are defined in the file, but I cant get a correct number in the file unless I open it manually and write for example 3, then it shows up, otherwise it dosn't.

Can you find my problem?

And then there is to write vinnare[].name empty, it doesn't work with NULL :/

struct vinnare{
    int ar;
    char namn[20];
};

    main(){
    int a, val, antalvinnareinlasning,test=0;

    struct vinnare *vinnare;

    FILE *file;
    file = fopen("F:\\Uppgifter.txt", "rt")
    if (file == NULL){
        printf("Hej2");
        vinnare = NULL;
        printf("Ange antal vinnare:");
        scanf("%d", &antalvinnareinlasning);
        vinnare = (struct vinnare *)malloc(antalvinnareinlasning*sizeof(struct vinnare));
        vinnare = inlasningTillFil(vinnare, antalvinnareinlasning);
    }
    else{
            **fscanf(file, "%b", &test);
            printf("%d",test);**

        fflush(stdin);
        getchar();

    }
}


struct vinnare *inlasningTillFil(struct vinnare *vinnare, int antalvinnareinlasning){
    int a, temp;

    FILE *file;
    file = fopen("F:\\Uppgifter.txt", "wt");
    **vinnare[0].ar = antalvinnareinlasning;**
    **strcpy(vinnare[0].namn, "");**                         //What should it say to make it empty?
    **fwrite(&vinnare[0], sizeof(struct vinnare),1, file);**


    for (a = 1; a < (antalvinnareinlasning + 1); a++){
        printf("year: ");
        scanf("%d", &temp);
        vinnare[a].ar = temp;
        fflush(stdin);

        printf("Winner that year:");
        fgets(vinnare[a].namn, 40, stdin);
        fflush(stdin);

        fwrite(&vinnare[a], sizeof(struct vinnare),1, file);
    }

}

Answer 1

fscanf parses strings (often written with fprintf); fread reads binary data (often written with fwrite). You're pairing fscanf and fwrite.

%b is also not a standard format specifier for fscanf, but since I suggest moving away from fscanf entirely in this case, I won't dig into that.