CMDP2063 Unix and C Programming

What is the correct syntax for a block comment in C?

• // Being weak is nothing to be ashamed of. Staying weak is.

• <!-- Being weak is nothing to be ashamed of. Staying weak is. -->

• /* Being weak is nothing to be ashamed of. Staying weak is. */

• #Being weak is nothing to be ashamed of. Staying weak is.

What happens if you try to use a // comment in C89?

• The code will compile successfully.

• It will cause a syntax error.

• The comment will be ignored, and the code will run normally.

• The // will be treated like a block comment.

Answer explanation

In C89 (also known as ANSI C), the // syntax for single-line comments is not supported. C89 only supports comments that are enclosed in /* ... */ for both single-line and multi-line comments. Using // in C89 will result in a syntax error because the compiler does not recognize it as valid comment syntax. Single-line comments using // were introduced in C99.

What will be the output of the following C program?

• No output

Answer explanation

In this program, the for loop iterates with i starting from 0 and increments until i is less than 5.

Inside the loop:

• When i is 3, the if (i == 3) condition is true, and the break statement is executed, which immediately exits the loop.

• Therefore, only the values 0, 1, and 2 are printed before the loop is terminated.

So, the output is 0 1 2.

What happens in this program when the square() function is called?

• Compile Error

Which of the following format specifiers is used to print a floating-point value using printf()?

• %f

• %d

• %c

• %s

What is the output of the following program in the image when using printf()?

• I have been learning %c for %d %s.

• I have been learning c for %d days.

• I have been learning for 42 days.

• I have been learning C for 42 days.

Answer explanation

Explanation: The printf() function uses format specifiers to insert the values:

• - %c is replaced by 'C'

• - %d is replaced by 42

• - %s is replaced by "days"

So, the final output is: "I have been learning C for 42 days."

What is the benefit of using forward declarations in C?

• To reduce the size of the executable file

• To allow the use of functions before they are defined in the source code

• To enhance the readability of the code

• To automatically generate documentation

What does the -Wall option do when compiling with gcc?

• It suppresses all warnings.

• It generates a log file of all warnings.

• It enables all warnings to help identify potential issues in the code.

• It compiles the program in C89 mode.

Answer explanation

The -Wall option in gcc enables a broad set of warning messages that help identify potential issues or questionable practices in the code.

These warnings can assist developers in finding and fixing possible bugs or improving code quality.

What command is used to run a compiled C program named school?

If you have a calc.c file, what is the correct way to include its corresponding header file?

Answer: ​​​ (a)   ​ ​

• #include <calc.h>
• #include calc.h
• #include "calc.c"
• #include "calc.h"