Computer Science questions in competitive exams stay close to fundamentals, which is good news if you revise the right five subjects. Coverage includes data structures, algorithms and complexity, operating systems, database management systems, computer networks, and computer organisation. Explanations show the trace or the state table where one helps, since seeing the intermediate steps is what makes the concept stick.
Which header file is required to use the printf() function?
Answer: B
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.
Q.22Easy
In C, which operator has the highest precedence?
Answer: C
Parentheses have the highest precedence in C. Expressions within parentheses are evaluated first, followed by arithmetic operators, then logical operators, and finally assignment operators.
Q.23Easy
What is the purpose of the break statement in a loop?
Answer: B
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.
Q.24Easy
In C programming, which of the following is NOT a valid data type?
Answer: C
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.
Q.25Easy
What will be the output of: int a = 10; int b = 20; int c = a + b; printf("%d", c);?
Answer: B
Variable 'a' is initialized to 10, 'b' is initialized to 20. When c = a + b, c becomes 10 + 20 = 30. Therefore, printf outputs 30.
Q.26Easy
Which of the following is used to declare a constant in C?
Answer: B
In C, the 'const' keyword is used to declare constants. Once a const variable is initialized, its value cannot be changed. Options A, C, and D are not valid C syntax.
Q.27Easy
What is the purpose of the return statement in a C function?
Answer: B
The return statement is used to exit a function and return a value (if any) to the calling function. If the function has return type void, no value is returned.
Q.28Easy
Which header file is required for using the printf() function?
Answer: B
stdio.h (Standard Input/Output header) contains declarations for printf(), scanf(), and other I/O functions.
Q.29Easy
What is the correct syntax to declare a constant in C?
Answer: D
Both 'const int x = 10;' and 'int const x = 10;' are valid ways to declare constants in C. The const keyword can appear before or after the type.
Q.30Easy
Which operator is used to access the value at an address in C?
Answer: B
The * operator is the dereference operator that accesses the value at a memory address. The & operator gets the address of a variable.
Q.31Easy
What does the sizeof() operator return?
Answer: B
sizeof() is a unary operator that returns the number of bytes occupied by a variable or data type in memory.
Q.32Easy
Which of the following is a correct way to initialize a 1D array in C?
Answer: D
All three methods are valid. Option A initializes with size 5, option B auto-determines size from initialization, and option C declares without initialization.
Q.33Easy
What is the size of an empty structure in C?
Answer: B
An empty structure in C has a size of 1 byte. This is to ensure each structure instance has a unique address in memory.
Q.34Easy
What will be the output of: char *s = "Hello"; printf("%d", strlen(s));
Answer: A
strlen() counts characters excluding the null terminator. "Hello" has 5 characters, so strlen(s) returns 5.
Q.35Easy
What will be the output of: #define MAX 10; int x = MAX; printf("%d", x);
Answer: A
The #define directive replaces MAX with 10 during preprocessing. So x = 10 and output is 10. (Note: semicolon after MAX is not needed but doesn't affect the output)
Q.36Easy
Which of the following correctly initializes a 2D array?
Answer: C
Both syntaxes are correct. C allows initializing 2D arrays with or without explicit braces for each row.
Q.37Easy
What will be the output of: printf("%d", 25);
Answer: B
Integer division truncates the decimal part. 25 = 2 (not 2.5) because both operands are integers.
Q.38Easy
What does the getchar() function do?
Answer: A
getchar() reads a single character from standard input (stdin) and returns its ASCII value.
Q.39Easy
What will be the output of: int a = 5, b = 5; if(a == b) printf("Equal"); else printf("Not Equal");
Answer: A
The == operator compares values. Since a and b both have value 5, the condition is true and "Equal" is printed.
Q.40Easy
Which header file is essential for using the printf() function in C?
Answer: B
The stdio.h header file contains declarations for standard input/output functions like printf(). Option A is C++, Option C is C++, and Option D is for memory allocation functions.
