Unit 6 C programming

Question 1

include <stdio.h></stdio.h>

Let’s say

int main()
{
printf(“Hello World”);
return 0
}

What is the run order of this program

Answer 1

• The C program runs in user mode
• The Program invokes printf()
• The C library intercepts this call and invokes the WriteFile() system call
• A system call is a request to the operating system to do something
• During the execution of a system call the mode is changed from user mode to kernel mode
• The library takes the value returned and passes it back to the program

Question 2

What are the three basic functions that take place in every C program

Answer 2

• Accepting of data as input
• Processing of data
• Generating output

Question 3

What is the keyboard input stream called

Answer 3

stdin

Question 4

What is the output stream

Answer 4

stdout

Question 5

What is the formatted input function

Answer 5

scanf()

Question 6

What is the formatted output function

Answer 6

printf()

Question 7

What are the unformatted input functions

Answer 7

getchar()
gets()

Question 8

What are the unformatted output functions

Answer 8

putchar()
puts()

Question 9

How would you read an integer from stdin

Answer 9

include main <stdio.h></stdio.h>

int main() {
int inputFromUser;
scanf(“%d”, &inputFromUser);
return 0;
}