Character arrays - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a character array in C?

A character array in C is a sequence of characters stored in contiguous memory locations. It is often used to store strings, which are sequences of characters ending with a special null character '\0'.

beginner

How do you declare a character array to hold the word "hello"?

You can declare it like this: <br>char word[6] = {'h', 'e', 'l', 'l', 'o', '\0'};<br>or simply: <br>char word[] = "hello";<br>The extra space is for the null character '\0' that marks the end of the string.

beginner

Why do character arrays used as strings in C end with a '\0' character?

The '\0' character, called the null terminator, tells functions where the string ends. Without it, functions like printf or strlen wouldn't know where the string stops and might read garbage data or cause errors.

beginner

How can you change the first character of a character array named 'name' to 'J'?

You can assign it directly like this: <br>name[0] = 'J';<br>This changes the first character stored in the array to 'J'.

intermediate

What happens if you forget to add the '\0' at the end of a character array used as a string?

If the '\0' is missing, functions that expect a string will keep reading memory past the array until they find a '\0'. This can cause unexpected behavior, crashes, or security issues.

Which of the following correctly declares a character array to store the string "cat"?

A char animal[3] = {'c', 'a', 't', '\0'};

B char animal[3] = "cat";

C char animal[] = {'c', 'a', 't'};

D char animal[4] = "cat";

Option D is correct because the array size must include space for the null terminator '\0'. So 4 characters are needed for 'c', 'a', 't', and '\0'.

What does the '\0' character represent in a character array?

A The end of the string

B A tab character

C A newline character

D A space character

The '\0' character is the null terminator that marks the end of a string in C.

How do you access the third character in a character array named 'word'?

A word[3]

B word[2]

C word(3)

D word{2}

Arrays in C are zero-indexed, so the third character is at index 2.

What will happen if you print a character array without a '\0' terminator using printf with %s?

A It prints the array correctly

B It prints nothing

C It may print extra garbage characters or crash

D It prints only the first character

Without the '\0', printf doesn't know where the string ends and may print extra memory or cause a crash.

Which of these is a valid way to initialize a character array with the string "dog"?

A char pet[] = "dog";

B char pet[3] = "dog";

C char pet[2] = {'d', 'o', 'g', '\0'};

D char pet = "dog";

Option A is valid because it lets the compiler size the array including the null terminator automatically.

Explain what a character array is and how it is used to store strings in C.

Think about how words are stored as letters in a row with a special end marker.

Describe why the null terminator '\0' is important in character arrays used as strings.

Consider what happens if you don't tell where the string ends.