Trailing newline character

I have a text file with 32 binary numbers, each one is in separate line and each number is 8 characters long. I want to store them in the mem array as strings.

Right now, this code looks like this:

    char mem[32][9];
    char line[9];

    FILE *file_pointer;
    file_pointer = fopen(filename, "r");

    if (file_pointer == NULL) {
        printf("Failed to open file \"%s\"!", filename);
    } else {
        int i = 0;
        while (fgets(line, sizeof line, file_pointer)) {
            memcpy(mem[i], line, 8);
            mem[i][8] = '\0';
            i++;
        }
    }
    fclose(file_pointer);

Unfortunately I still get newline characters in line, so my array is not displaying properly.

This is my console when I am printing the array:

00      00110100
01

02      01111100
03

04      10011100
05

06      10010101
etc...

My code for printing the array:

for (i = 0; i < 32; i++) {
    if (i >= 10) {
        printf("%d", i);
    } else {
        printf("%c%d", '0', i);
    }
    printf("\t%s\n", mem[i]);
}

I tried also using:

strtok(line, "\n");

line[strcspn(line, "\r\n")] = '\0';

Solution

Some notes about your code:

You must make line longer so fgets() can read the '\n' into line. Currently it breaks each line into an 8 byte chunk and an empty line with the newline character.
You should prevent the while loop from reading beyond the end of the array.

Here is an improved version

    char mem[32][9] = { 0 };
    char line[80];

    FILE *file_pointer = fopen(filename, "r");

    if (file_pointer == NULL) {
        fprintf(stderr, "Failed to open file \"%s\"!\n", filename);
    } else {
        int i = 0;
        while (i < 32 && fgets(line, sizeof line, file_pointer)) {
            strncat(mem[i], line, 8);
            i++;
        }
        if (i < 32) {
            fprintf(stderr, "Missing values in file \"%s\": found %d lines\n",
                    filename, i);
        }
        fclose(file_pointer);
    }

You could also simplify the printing code this way:

    for (int i = 0; i < 32; i++) {
        printf("%02d\t%s\n", i, mem[i]);
    }

Note that if you are certain about the file format, you can simplify the reading code this way:

    char mem[32][9];
    char line[80];

    FILE *file_pointer = fopen(filename, "r");

    if (file_pointer == NULL) {
        fprintf(stderr, "Failed to open file \"%s\"!\n", filename);
    } else {
        if (fread(mem, 9, 32, fp) != 32) {
            fprintf(stderr, "Missing bytes in file %s\n", filename);
        } else {
            for (int i = 0; i < 32; i++) {
                mem[i][8] = '\0';
            }
        }
        fclose(file_pointer);
    }

You might also want to verify that the strings in mem[] contain exactly 8 hexadecimal digits with a simple loop and using the isxdigit() function from <ctype.h>:

            for (int i = 0; i < 32; i++) {
                int j;
                for (j = 0; j < 8; i++) {
                    if (!isxdigit((unsigned char)mem[i][j])
                        break;
                }
                if (j != 8 || mem[i][8] != \n') {
                    fprintf("invalid data on line %d\n", i + 1);
                }
                mem[i][8] = '\0';
            }