Ch1 Systems Programming and C Basics II

Question 1

What is the purpose of the main() function in a C program?

Answer 1

The main() function is the entry point of a C program. Execution of the program starts and ends here.

Question 2

What is the difference between printf() and scanf() format specifiers %d and %f?

Answer 2

• %d is used for integers.
• %f is used for floating-point numbers.

Question 3

What is the purpose of the \n character in a printf() statement?

Answer 3

The \n character is used to insert a newline, moving the cursor to the beginning of the next line.

Question 4

What is the purpose of the #include <math.h> directive in a C program?

Answer 4

The #include <math.h> directive includes the math library, which provides functions like sin(), cos(), pow(), and sqrt().

Question 5

What is the difference between float and double in C?

Answer 5

• float is a single-precision floating-point number (typically 4 bytes).
• double is a double-precision floating-point number (typically 8 bytes).

Question 6

What is the purpose of the sizeof operator in C?

Answer 6

The sizeof operator returns the size, in bytes, of a variable or data type.

Question 7

What is the difference between int and unsigned int in C?

Answer 7

• int can represent both positive and negative numbers.
• unsigned int can only represent non-negative numbers (zero and positive).

Question 8

What is the purpose of the if statement in C?

Answer 8

The if statement is used to execute a block of code only if a specified condition is true.

Question 9

What is the purpose of the else statement in C?

Answer 9

The else statement is used to execute a block of code if the condition in the if statement is false.

Question 10

What is the purpose of the switch statement in C?

Answer 10

The switch statement is used to execute one of many code blocks based on the value of a variable or expression.

Question 11

What is the purpose of the for loop in C?

Answer 11

The for loop is used to repeatedly execute a block of code a specific number of times.

Question 12

What is the purpose of the while loop in C?

Answer 12

The while loop is used to repeatedly execute a block of code as long as a specified condition is true.

Question 13

What is the purpose of the do-while loop in C?

Answer 13

The do-while loop is used to repeatedly execute a block of code at least once, and then continue as long as a specified condition is true.

Question 14

What is the purpose of the break statement in a switch statement?

Answer 14

The break statement is used to exit the switch statement, preventing fall-through to the next case.

Question 15

What is the purpose of the continue statement in a loop?

Answer 15

The continue statement skips the rest of the current iteration and proceeds to the next iteration of the loop.

Question 16

What is the purpose of the return statement in a function?

Answer 16

The return statement is used to exit a function and optionally return a value to the caller.

Question 17

What is the purpose of the void keyword in a function declaration?

Answer 17

The void keyword indicates that the function does not return a value.

Question 18

What is the purpose of the static keyword in C?

Answer 18

The static keyword can be used to:
- Limit the scope of a variable or function to the file in which it is declared.
- Preserve the value of a local variable between function calls.

Question 19

What is the purpose of the const keyword in C?

Answer 19

The const keyword is used to declare a variable as read-only, meaning its value cannot be changed after initialization.

Question 20

What is the purpose of the typedef keyword in C?

Answer 20

The typedef keyword is used to create an alias for a data type, making it easier to use and understand.