Which of the following correctly declares and initializes a 2D array?
Answer: C
Both syntax forms are valid in C. Elements can be provided in nested braces or as a linear list, and they fill row by row.
Q.202Medium
What is the relationship between array name and pointer in C?
Answer: A
Array names decay to pointers to the first element in expressions, but they are not truly pointer variables. The array name cannot be reassigned.
Q.203Medium
If str = "Hello", what is the value of str[5]?
Answer: A
"Hello" has 5 characters, so valid indices are 0-4. Index 5 contains the null terminator '\0' that marks the end of the string.
Q.204Medium
In a 2D array int matrix[4][5], which statement about memory layout is true?
Answer: A
C uses row-major order for 2D arrays. matrix[0][0], matrix[0][1]...matrix[0][4], matrix[1][0]... are stored sequentially in memory.
Q.205Medium
What is the output of sizeof(arr)/sizeof(arr[0]) when arr is declared as int arr[10]?
Answer: A
This expression calculates array length. sizeof(arr) gives total bytes (40 on 32-bit system), sizeof(arr[0]) gives bytes per element (4), so 440=10.
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Q.206Medium
Which string function modifies the original string in-place?
Answer: D
Both strtok() (modifies by replacing delimiters with '\0') and strcpy() (copies and overwrites destination) modify strings in-place.
Q.207Medium
What happens when you try to modify a string literal in C?
Answer: C
String literals are stored in read-only memory. Attempting modification causes undefined behavior (often segmentation fault). This is why char *str = "text"; str[0]='T'; is dangerous.
Q.208Medium
What is the time complexity of inserting an element at the beginning of an unsorted array?
Answer: B
Inserting at the beginning requires shifting all n elements one position right, making it O(n). Insertion at the end is O(1) if space exists.
Q.209Medium
Which function is used to find the first occurrence of a character in a string?
Answer: B
strchr() finds the first occurrence of a character. strrchr() finds the last occurrence. strstr() finds substrings.
Q.210Medium
What will be the output?
char arr[] = "ABC";
printf("%d", sizeof(arr));
Answer: B
sizeof includes the null terminator. "ABC" has 4 bytes (A, B, C, \0).
Q.211Medium
Consider the code: int *p; int arr[5] = {10, 20, 30, 40, 50}; p = arr; What is *(p+2)?
Answer: B
p points to arr[0]. p+2 points to arr[2], which contains 30.
Q.212Medium
Which of the following will correctly compare two strings?
Answer: B
A compares pointers, not string content. strcmp() compares actual string values character by character.
Q.213Medium
What is the correct syntax to concatenate two strings safely in modern C?
Answer: D
strcat() is unsafe due to buffer overflow risk. strncat() and sprintf() provide bounds checking.
Q.214Medium
What does the following code do?
char str[] = "HELLO";
for(int i = 0; str[i]; i++) str[i] = str[i] + 32;
Answer: A
Adding 32 to uppercase ASCII values converts them to lowercase (A=65, a=97, difference=32).
Q.215Medium
Consider: char str[10]; strcpy(str, "Hello"); What is the state of memory after this?
Answer: C
strcpy copies "Hello" and adds null terminator at position 5. Positions 6-9 remain uninitialized.
Q.216Medium
What does strtok(str, delim) return on each call until the string ends?
Answer: B
strtok() returns a pointer to the next token separated by the delimiter. Returns NULL when no more tokens exist.
Q.217Medium
What is the correct way to declare a pointer to a character array?
Answer: B
char (*ptr)[] declares ptr as a pointer to a character array. The parentheses are crucial for correct precedence.
Q.218Medium
What happens when you try to modify a string literal in C?
char *str = "Hello";
str[0] = 'J';
Answer: B
String literals are stored in read-only memory. Attempting to modify them causes undefined behavior or segmentation fault.
Q.219Medium
Which of the following correctly reverses a string in-place?
Answer: A
strrev() is a non-standard but commonly used function (available in string.h in some compilers) that reverses a string in-place.
Q.220Medium
What is the output of the following code?
char str[] = "GATE";
printf("%d", sizeof(str));
Answer: B
sizeof(str) returns 5 because the array includes 4 characters plus 1 null terminator.
