Seminar 3 - EDA25

What's the best practice when loading a file in C?

• Simply open it.

• Open it, check that it can be accessed and close it.

• Open it and close it.

What's the difference between the following lines?

(I) FILE *f = fopen("example.txt", "r");

(II) FILE *f = fopen("example.txt", "w");

(III) FILE *f = fopen("example.txt", "a");

• (I) reads the file in reading mode; (II) reads it in writing mode; (III) reads it in append mode

• (I) reads the file in reading mode; (II) reads it in writing mode; (III) is not correct

• They are equivalent

What's the difference between the reading mode ("r") and the writing mode ("w")?

• The reading mode allows multiple programs to access the same file, whereas the writing mode just one program.

• Both modes allow multiple programs to access the same file.

• Both modes allow only one program to access the same file.

What's the difference between the writing mode ("w") and the append mode ("a")?

• They are equivalent, but the append mode allow multiple programs to access the same file.

• The append mode does not exist.

• The writing mode erases the contents of the file before making any changes, whereas the append mode adds the new changes at the end.

How does fscanf(...) handle whitespace (e.g., spaces, tabs, or newlines) when reading input?

• It parses them normally.

• It skips them.

Consider that p is an integer and f a file pointer. What does fscanf(f, "%d", &p) do?

• It parses the formatted input, i.e., "%d", from file f, stores it in p and moves to the next character.

• It parses the formatted input, i.e., "%d", from file f, and stores it in p.

• It waits for the user's input in the file f and stores it in p.

Consider that p and q are integers and f a file pointer. What does fscanf(f, "%d %d", &p, &q) return?

• True if it has been successfully parsed; false, otherwise.

• The number of matches in the formatted input, i.e., 2.

Consider that p is an integer and f a file pointer. What happens when fscanf(f, "%d", &p) encounters non-integer input (e.g., the file contains "hello")?

• fscanf(...) will store 0 in p.

• fscanf(...) will throw an error and terminate the program.

• fscanf(...) will return 0 and leave p unmodified.

When does a segmentation fault occur?

• When a program tries to access a restricted or invalid memory location.

• When a program encounters a logical error in the code.

• When a program runs out of memory.

What's the difference between malloc and realloc?

• malloc is used to deallocate memory, while realloc is used to allocate memory.

• They are equivalent.

• malloc allocates a new block of memory, while realloc resizes an existing block of memory.