Reading from files in C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a file named "data.txt" for reading.

C

#include <stdio.h>

int main() {
    FILE *file = fopen("data.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'

A"w"

B"r"

C"a"

D"rw"

Attempts:

3 left

💡 Hint

Common Mistakes

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

Using "a" which opens the file for appending.

To read from a file, you open it with mode "r".

2fill in blank

medium

Complete the code to read a single character from the file.

C

#include <stdio.h>

int main() {
    FILE *file = fopen("data.txt", "r");
    if (file == NULL) {
        return 1;
    }
    int ch = [1](file);
    if (ch != EOF) {
        printf("Character read: %c\n", ch);
    }
    fclose(file);
    return 0;
}

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

Afputc

Bfgets

Cfread

Dfgetc

Attempts:

3 left

💡 Hint

Common Mistakes

Using fputc which writes a character to a file.

Using fgets which reads a string, not a single character.

fgetc reads a single character from a file.

3fill in blank

hard

Fix the error in the code to read a line from the file into buffer.

C

#include <stdio.h>

int main() {
    char buffer[100];
    FILE *file = fopen("data.txt", "r");
    if (file == NULL) {
        return 1;
    }
    if ([1](buffer, 100, file) != NULL) {
        printf("Line: %s", buffer);
    }
    fclose(file);
    return 0;
}

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

Afgets

Bfgetc

Cfread

Dfputc

Attempts:

3 left

💡 Hint

Common Mistakes

Using fgetc which reads only one character.

Using fread which reads raw bytes and needs size parameters.

fgets reads a line from a file into a buffer.

4fill in blank

hard

Fill both blanks to read the file character by character until EOF.

C

#include <stdio.h>

int main() {
    FILE *file = fopen("data.txt", "r");
    if (file == NULL) {
        return 1;
    }
    int ch;
    while ((ch = [1](file)) [2] EOF) {
        putchar(ch);
    }
    fclose(file);
    return 0;
}

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

Afgetc

Bfputc

C!=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using fputc which writes characters.

Using == which would stop at the first character.

Use fgetc to read each character and loop while it is not EOF.

5fill in blank

hard

Fill all three blanks to read integers from a file until fscanf fails.

C

#include <stdio.h>

int main() {
    FILE *file = fopen("numbers.txt", "r");
    if (file == NULL) {
        return 1;
    }
    int num;
    while ([1](file, [2], &num) == [3]) {
        printf("Number: %d\n", num);
    }
    fclose(file);
    return 0;
}

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

Afscanf

B"%d"

C1

Dfgets

Attempts:

3 left

💡 Hint

Common Mistakes

Using fgets which reads strings, not formatted integers.

Checking for return value 0 or EOF instead of 1.

fscanf reads formatted input; "%d" specifies integer format; it returns 1 when one item is successfully read.