Why file handling is required in C - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a file for reading.

C

#include <stdio.h>

int main() {
    FILE *file = fopen("example.txt", "[1]");
    if (file == NULL) {
        printf("Failed to open file.\n");
        return 1;
    }
    fclose(file);
    return 0;
}

Drag options to blanks, or click blank then click option'

Aw

Ba

Cr

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using "w" mode which opens file for writing and erases content.

Using "a" mode which opens file for appending.

To read from a file, you must open it in read mode using "r".

2fill in blank

medium

Complete the code to write a string to a file.

C

#include <stdio.h>

int main() {
    FILE *file = fopen("output.txt", "[1]");
    if (file == NULL) {
        printf("Cannot open file.\n");
        return 1;
    }
    fprintf(file, "Hello, file handling!\n");
    fclose(file);
    return 0;
}

Drag options to blanks, or click blank then click option'

Aw

Br

Ca

Drb

Attempts:

3 left

💡 Hint

Common Mistakes

Using "r" mode which is for reading only.

Using "rb" which is for reading binary files.

To write to a file, open it in write mode using "w".

3fill in blank

hard

Fix the error in the code to append text to an existing file.

C

#include <stdio.h>

int main() {
    FILE *file = fopen("log.txt", "[1]");
    if (file == NULL) {
        printf("Error opening file.\n");
        return 1;
    }
    fprintf(file, "New log entry\n");
    fclose(file);
    return 0;
}

Drag options to blanks, or click blank then click option'

Aw

Ba

Cw+

Dr

Attempts:

3 left

💡 Hint

Common Mistakes

Using "w" mode which overwrites the file.

Using "r" mode which does not allow writing.

To add data at the end of a file without erasing existing content, use append mode "a".

4fill in blank

hard

Fill both blanks to read a character from a file and check for end of file.

C

#include <stdio.h>

int main() {
    FILE *file = fopen("data.txt", "r");
    int ch;
    if (file == NULL) {
        printf("Cannot open file.\n");
        return 1;
    }
    while ((ch = [1](file)) != [2]) {
        putchar(ch);
    }
    fclose(file);
    return 0;
}

Drag options to blanks, or click blank then click option'

Afgetc

BEOF

Cgetc

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using NULL instead of EOF to check end of file.

Using getc without comparing to EOF.

Use fgetc to read a character from the file and compare it with EOF to detect end of file.

5fill in blank

hard

Fill all three blanks to write and then read a string from a file.

C

#include <stdio.h>

int main() {
    char str[50];
    FILE *file = fopen("test.txt", "[1]");
    if (file == NULL) {
        printf("File open error.\n");
        return 1;
    }
    fprintf(file, "Hello World\n");
    fclose(file);

    file = fopen("test.txt", "[2]");
    if (file == NULL) {
        printf("File open error.\n");
        return 1;
    }
    fgets(str, sizeof(str), file);
    printf("Read from file: %s", [3]);
    fclose(file);
    return 0;
}

Drag options to blanks, or click blank then click option'

Aw

Br

Cstr

Dfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using "r" mode to write the file.

Printing the file pointer instead of the string.

Open the file in write mode "w" to write, then in read mode "r" to read. Use the variable str to print the read string.