7_sem

What will be the output? int x = 10; printf("%d %d", x, x++);

• 10 11

• 11 10

• Undefined behavior

• 10 10

Answer explanation

The expression 'x++' modifies 'x' after its current value is used. Since 'x' is evaluated twice without a sequence point, it leads to undefined behavior. Thus, the output is not predictable, making 'Undefined behavior' the correct choice.

Which keyword is used to avoid multiple inclusions of header files?

• static

• extern

• #pragma once

• const

Answer explanation

The keyword #pragma once is used in C and C++ to prevent multiple inclusions of the same header file, ensuring that the file is included only once per compilation unit. This helps avoid redefinition errors.

Output? printf("%d", sizeof("Hello"));

• 5

• 6

• 4

• Compiler error

Answer explanation

The expression sizeof("Hello") calculates the size of the string literal, which includes the null terminator. "Hello" has 5 characters plus 1 for the null terminator, totaling 6. Thus, the correct answer is 6.

Which sorting has best case O(n)?

• Bubble sort

• Insertion sort

• Merge sort

• Quick sort

Answer explanation

Insertion sort has a best case time complexity of O(n) when the input array is already sorted. In this scenario, it only requires a single pass through the array, making it more efficient than the other sorting algorithms listed.

Which operator has the highest precedence?

• * (dereference)

• ++

• ()

• []

Answer explanation

The operator with the highest precedence is '()' (parentheses), which is used for grouping expressions and function calls. It takes precedence over dereference, increment, and array subscripting operators.

Which storage class allows local persistence of variables?

• auto

• static

• register

• extern

Answer explanation

The 'static' storage class allows variables to maintain their value between function calls, providing local persistence. In contrast, 'auto' and 'register' do not retain values after the function exits, and 'extern' is used for global variables.

Which of the following is not a valid string function in standard C?

• strcpy()

• strcat()

• strrev()

• strlen()

Answer explanation

The function strrev() is not part of the standard C library. The other functions, strcpy(), strcat(), and strlen(), are valid string functions used for copying, concatenating, and measuring string length, respectively.

Output? a=[1,2,3] b=a b.append(4) print(a)

• [1,2,3]

• [1,2,3,4]

• Error

• None

Answer explanation

In Python, when you assign b = a, both variables reference the same list. Thus, appending 4 to b also modifies a. Therefore, print(a) outputs [1, 2, 3, 4]. The correct answer is [1,2,3,4].

Which of these is immutable?

• list

• set

• dict

• tuple

Answer explanation

A tuple is immutable, meaning its elements cannot be changed after creation. In contrast, lists, sets, and dictionaries are mutable, allowing modifications. Therefore, the correct answer is tuple.

Output? print(0.1 + 0.2 == 0.3)

• True

• False

• Error

• Depends

Answer explanation

The expression 0.1 + 0.2 does not exactly equal 0.3 due to floating-point precision errors in binary representation. Therefore, the output of the comparison is False.