Binary Read Count

The count returned by fread tells the loop how many binary items were loaded.

binary_read_count.c

#include <stdio.h>

int main(void) {
    int count = ;
    int values[4] = {2, 4, 6, 8};
    int loaded[4] = {0, 0, 0, 0};
    int sum = 0;

    FILE *out = fopen("egtry_c17_count.bin", "wb");
    fwrite(values, sizeof(values[0]), count, out);
    fclose(out);

    FILE *in = fopen("egtry_c17_count.bin", "rb");
    int read = (int)fread(loaded, sizeof(loaded[0]), 4, in);
    fclose(in);
    remove("egtry_c17_count.bin");

    for (int i = 0; i < read; i++) {
        sum = sum + loaded[i];
    }

    printf("read=%d sum=%d\n", read, sum);
    return 0;
}

#include <stdio.h>

int main(void) {
    int count = ;
    int values[4] = {2, 4, 6, 8};
    int loaded[4] = {0, 0, 0, 0};
    int sum = 0;

    FILE *out = fopen("egtry_c17_count.bin", "wb");
    fwrite(values, sizeof(values[0]), count, out);
    fclose(out);

    FILE *in = fopen("egtry_c17_count.bin", "rb");
    int read = (int)fread(loaded, sizeof(loaded[0]), 4, in);
    fclose(in);
    remove("egtry_c17_count.bin");

    for (int i = 0; i < read; i++) {
        sum = sum + loaded[i];
    }

    printf("read=%d sum=%d\n", read, sum);
    return 0;
}

#include <stdio.h>

int main(void) {
    int count = ;
    int values[4] = {2, 4, 6, 8};
    int loaded[4] = {0, 0, 0, 0};
    int sum = 0;

    FILE *out = fopen("egtry_c17_count.bin", "wb");
    fwrite(values, sizeof(values[0]), count, out);
    fclose(out);

    FILE *in = fopen("egtry_c17_count.bin", "rb");
    int read = (int)fread(loaded, sizeof(loaded[0]), 4, in);
    fclose(in);
    remove("egtry_c17_count.bin");

    for (int i = 0; i < read; i++) {
        sum = sum + loaded[i];
    }

    printf("read=%d sum=%d\n", read, sum);
    return 0;
}

read count The returned item count is safer than assuming the full buffer was filled.

bounded loop The sum loop uses the returned count as its upper bound.