What is the difference between file modes `"r+"` and `"w+"` in C?

`"r+"` opens an existing file for reading and writing without truncating, while `"w+"` creates or truncates the file for reading and writing

`"r+"` creates a new file, while `"w+"` opens an existing file

`"r+"` is used for binary files, while `"w+"` is used for text files

There is no difference between `"r+"` and `"w+"`

Consider the following code snippet: ```c FILE *fp = fopen("data.txt", "r"); fclose(fp); ``` What happens if `"data.txt"` does not exist when this code is executed?

`fopen()` returns `NULL` and `fclose()` may cause undefined behavior

A new empty file named `"data.txt"` is created

The program automatically switches to write mode

What is the purpose of the `rewind()` function in C file handling?

It moves the file pointer to the beginning of the file

It closes the file and reopens it from the beginning

It deletes all content in the file and resets it

It moves the file pointer to the end of the file

Analyze the following code. What will be the output if `"test.txt"` initially contains the text `"Hello"`: ```c FILE *fp = fopen("test.txt", "a"); fputs(" World", fp); fclose(fp); ```

The file will be overwritten with `" World"` only

A programmer wants to read binary data of 10 integers from a file. Which function call correctly reads this data into an array `arr` from file pointer `fp`?

`fread(arr, sizeof(int), 10, fp);`

`fread(fp, sizeof(int), 10, arr);`

`fgets(arr, sizeof(int) * 10, fp);`

A student writes the following code to count the number of characters in a file. Identify the logical error: ```c FILE *fp = fopen("data.txt", "r"); int count = 0; while (!feof(fp)) { fgetc(fp); count++; } printf("%d", count); fclose(fp); ```

The count will be one more than the actual number of characters because `feof()` is only set after a failed read

`fgetc()` cannot be used with a `while` loop

The file should be opened in `"w"` mode for reading characters

`fclose()` should be called before `printf()`

A programmer needs to copy the contents of `"source.txt"` into `"destination.txt"`. Which of the following approaches is correct?

Open `"source.txt"` in `"r"` mode and `"destination.txt"` in `"w"` mode, then read characters from source and write them to destination until `EOF`

Open `"source.txt"` in `"w"` mode and `"destination.txt"` in `"r"` mode, then use `fgetc()` to transfer data

Open both files in `"r+"` mode and use `fseek()` to copy data between them

Open `"source.txt"` in `"a"` mode and `"destination.txt"` in `"w"` mode, then use `fputs()` to transfer data

Consider the following code that attempts to write and then read back data from a file: ```c FILE *fp = fopen("data.txt", "w+"); fprintf(fp, "Hello"); char buffer[10]; fscanf(fp, "%s", buffer); printf("%s", buffer); fclose(fp); ``` Why will `buffer` not contain `"Hello"` when printed?

After writing `"Hello"`, the file pointer is at the end of the file, so `fscanf()` reads from the end and finds nothing

`fprintf()` cannot be used with `"w+"` mode

`fscanf()` requires the file to be closed and reopened before reading

`"w+"` mode does not support reading operations

Mastering File Handling in C

Authored by Dean CSE

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MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which of the following file modes is used to open a file for reading only in C?

`"w"`

`"a"`

`"r"`

`"rw"`

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What does the file mode `"w"` do when used with `fopen()` in C?

Opens a file for reading only

Opens a file for writing, creating it if it doesn't exist and truncating it if it does

Opens a file for appending data at the end

Opens a file for both reading and writing without truncating

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which function is used to open a file in C?

`openfile()`

`fileopen()`

`fopen()`

`open()`

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the return type of the `fopen()` function in C?

`int`

`char`

`void`

`FILE *`

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which of the following functions is used to read a single character from a file in C?

`fscanf()`

`fgetc()`

`fread()`

`fgets()`

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What value does `fopen()` return if it fails to open a file?

`0`

`-1`

`NULL`

`EOF`

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which file mode should be used to add data to the end of an existing file without deleting its current contents?

`"w"`

`"r+"`

`"a"`

`"w+"`

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Mastering File Handling in C

Which of the following file modes is used to open a file for reading only in C?

What does the file mode `"w"` do when used with `fopen()` in C?

Which function is used to open a file in C?

What is the return type of the `fopen()` function in C?

Which of the following functions is used to read a single character from a file in C?

What value does `fopen()` return if it fails to open a file?

Which file mode should be used to add data to the end of an existing file without deleting its current contents?

What is the difference between file modes `"r+"` and `"w+"` in C?

Which of the following correctly reads a formatted integer value from a file pointed to by `fp` in C?

What does the `feof()` function return when the end of a file has been reached?

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