Programming in C MCQ - Constants, Variables and Data Types

21 Which of the following comments regarding the reading of a string, using scanf(with optional) and get is true?

A comment is used to document source code and is ignored by the compiler as executable program logic. C supports block comments enclosed between /* and */ and, since C99, single-line comments beginning with //. Comments improve readability but do not change the result of a correctly written program.

22 If integer needs two bytes of storage, then maximum value of a signed integer is

In signed magnitude form, one bit is dedicated to store the sign(e.g., 1 for negative and otherwise). Only the remaining 15 bits are available to store the magnitude. Hence the answer.

23 The minimum number of temporary variables needed to swap the contents of two variables is

Without any temporary variable, one can swap two given variables.

24 If s and b are integers then purpose of the following program fragment is to
b = s + b ;
s = b - s ;
b = b - s ;

Swapping two integer variables means exchanging their values. If s initially contains 10 and b contains 20, after swapping, s contains 20 and b contains 10. A temporary variable is one common way to perform the exchange.

25 If integer needs two bytes of storage, then maximum value of an unsigned integer is

For an integer representation using two bytes, there are 16 bits in total. A signed integer commonly uses one bit to represent the sign and the remaining 15 bits for the magnitude or value representation, depending on the signed integer representation. In modern two-complement systems, a signed 16-bit integer normally ranges from -32768 to 32767. The C language does not guarantee that int occupies exactly two bytes.