Which function is used to find the first occurrence of a character in a string?
strchr() finds the first occurrence of a character. strrchr() finds the last occurrence. strstr() finds substrings.
What will be the output?
char arr[] = "ABC";
printf("%d", sizeof(arr));
sizeof includes the null terminator. "ABC" has 4 bytes (A, B, C, \0).
Consider the code: int *p; int arr[5] = {10, 20, 30, 40, 50}; p = arr; What is *(p+2)?
p points to arr[0]. p+2 points to arr[2], which contains 30.
What will be printed?
char *str = "Hello";
printf("%c", str[1]);
str[1] accesses the second character of the string, which is 'e'.
Which of the following will correctly compare two strings?
A compares pointers, not string content. strcmp() compares actual string values character by character.
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What is the correct syntax to concatenate two strings safely in modern C?
strcat() is unsafe due to buffer overflow risk. strncat() and sprintf() provide bounds checking.
Predict the output:
int arr[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
printf("%d", arr[1][2]);
arr[1][2] refers to row 1, column 2, which contains 6.
What does the following code do?
char str[] = "HELLO";
for(int i = 0; str[i]; i++) str[i] = str[i] + 32;
Adding 32 to uppercase ASCII values converts them to lowercase (A=65, a=97, difference=32).
In a dynamic 2D array created as: int arr = (int)malloc(rows * sizeof(int*)); What is the next step?
After allocating the array of pointers, each row must be allocated separately.
What will happen?
char arr[5] = "Hello";
printf("%d", strlen(arr));
Array is too small. "Hello" needs 6 bytes including null terminator, but only 5 are allocated. This causes buffer overflow.
Consider: char str[10]; strcpy(str, "Hello"); What is the state of memory after this?
strcpy copies "Hello" and adds null terminator at position 5. Positions 6-9 remain uninitialized.
What is the output?
int arr[] = {10, 20, 30, 40};
int *p = arr;
printf("%d", p[2]);
p points to arr[0]. p[2] is equivalent to *(p+2), which points to arr[2] = 30.
What does strtok(str, delim) return on each call until the string ends?
strtok() returns a pointer to the next token separated by the delimiter. Returns NULL when no more tokens exist.
What is the maximum size of a string that can be stored in char str[50]?
A char array of size 50 can store maximum 49 characters because the last position is reserved for the null terminator '\0'.
Which function is used to find the length of a string in C?
strlen() is the standard library function defined in string.h that returns the length of a string excluding the null terminator.
How many bytes does a 2D array int arr[3][4] occupy in memory?
int occupies 4 bytes. Array size is 3×4 = 12 elements. Total: 12 × 4 = 48 bytes.
What is the correct way to declare a pointer to a character array?
char (*ptr)[] declares ptr as a pointer to a character array. The parentheses are crucial for correct precedence.
What happens when you try to modify a string literal in C?
char *str = "Hello";
str[0] = 'J';
String literals are stored in read-only memory. Attempting to modify them causes undefined behavior or segmentation fault.
Which of the following correctly reverses a string in-place?
strrev() is a non-standard but commonly used function (available in string.h in some compilers) that reverses a string in-place.
What is the output of the following code?
char str[] = "GATE";
printf("%d", sizeof(str));
sizeof(str) returns 5 because the array includes 4 characters plus 1 null terminator.
