Computer Knowledge - MCQ Practice Questions

C does not perform bounds checking on arrays. Accessing beyond array bounds results in undefined behavior - it may access garbage values, crash, or seem to work without error. This is a common source of bugs.

x++ is post-increment. First printf uses current value (10), then x is incremented. Second printf uses new value (11). Output: 1011

Both char s[] (array notation) and char *s (pointer notation) are valid ways to pass strings to functions in C. C does not have a built-in string type; strings are represented as character arrays or pointers to char.

In a 32-bit system, the int data type typically occupies 4 bytes (32 bits). This is the standard size for integer types on most 32-bit architectures.

The stdio.h (Standard Input Output) header file contains declarations for printf(), scanf(), and other input/output functions. It is essential for console I/O operations.

Parentheses have the highest precedence in C. Expressions within parentheses are evaluated first, followed by arithmetic operators, then logical operators, and finally assignment operators.

The break statement exits or terminates the current loop immediately. Option D describes continue (which skips to next iteration), while break actually exits the loop.

The correct syntax for declaring a pointer to an integer is 'int *ptr;' where the asterisk (*) indicates that ptr is a pointer. The placement of * before the variable name is crucial.

When %d format specifier is used with a char variable, it prints the ASCII value. The ASCII value of 'A' is 65. If it were 'a', the value would be 97.

malloc() (memory allocation) is the standard function in C for dynamic memory allocation. It returns a void pointer to the allocated memory. The syntax is: ptr = (type*)malloc(size);

Array indexing in C starts from 0. str[0]='H', str[1]='e', str[2]='l', str[3]='l', str[4]='o', str[5]='\0'. Therefore, str[1] is 'e'.

strcmp() is the standard library function used to compare two strings. It returns 0 if strings are equal, negative if first string is less, and positive if first string is greater. It's declared in string.h.

p is a pointer to x, so &x gives the address of x. *p (dereferencing) gives the value stored at that address, which is 5. The output will be 5.

In C, identifiers can only contain alphanumeric characters (a-z, A-Z, 0-9) and underscores (_), and must start with a letter or underscore. The dollar sign ($)isnotallowed,makin{g}^{\prime }my$var' invalid.

x++ is post-increment (returns 5, then x becomes 6), ++x is pre-increment (x becomes 7, then returns 7). The order of evaluation in printf is implementation-dependent, but typically right to left, giving 5 7.

Structure allocates separate memory for each member (total size = sum of all members). Union shares a single memory location among all members (total size = size of largest member). This is a fundamental difference in memory allocation.

The correct syntax is 'void function(void);' where 'void' in parentheses explicitly states no parameters. Option B is also valid in C (defaults to no parameters), but option A is more explicit and portable across C standards.

typedef creates an alias (synonym) for existing data types. For example, 'typedef int Integer;' creates 'Integer' as an alias for 'int'. This improves code readability and portability. It doesn't create entirely new types, but provides alternative names.

In C, 'string' is not a primitive data type. C uses 'char' arrays to represent strings. The valid primitive data types are int, float, double, char, void, and their variants.

Variable 'a' is initialized to 10, 'b' is initialized to 20. When c = a + b, c becomes 10 + 20 = 30. Therefore, printf outputs 30.