Answer / vishnu948923

system calls are provided by the system and are executed in
the system kernel. They are entry points into the kernel and
are therefore NOT linked into your program. These are not
portable calls.
· Library calls include the ANSI C standard library and
are therefore portable. These functions are linked into your
program.
It is worth noting that, because system calls are part of
the O/S. The program has to make a context switch to the
kernel when they are called and because of this, they have a
high startup overhead. The upside is that the time executing
these routines is assigned to the OS and not the user program.

Answer / eng abedalmohdi almomani

system call can be called from either kernel space or user
space(in this case include switch to privilage mode) and
executed in kernel space while library called only from
user programm and may call systemcall to perform it is
function like "printf" that need "write" system call while
other not need kernel at all like sin(),cos().....

systemcall examples : write,read,close,mmap,open,.......
library examples: fopen,fclose,printf,scanf,fscanf,.....

what will be the output of this program? #include<stdio.h> #define cube(x) x*x*x void main() { int i,j=5; i=cube(j+3); printf("i=%d",i); }

6 Answers   IBM,

---

Just came across this question, felt worth sharing, so here it is I want you to make a C/C++ program that for any positive integer n will print all the positive integers from 1 up to it and then back again! Let's say n=5 I want the program to print: 1 2 3 4 5 4 3 2 1. Too easy you say? Okay then... You can ONLY USE: 1 for loop 1 printf/cout statement 2 integers( i and n) and as many operations you want. NO if statements, NO ternary operators, NO tables, NO pointers, NO functions!

1 Answers  

---

What is typeof in c?

0 Answers  

---

Differentiate between functions getch() and getche().

0 Answers  

---

main(){char *str;scanf("%s",str);printf("%s",str); }The error in the above program is: a) Variable 'str' is not initialised b) Format control for a string is not %s c) Parameter to scanf is passed by value. It should be an address d) none

0 Answers  

---

Can a variable be both constant and volatile?

0 Answers  

---

Tell me can the size of an array be declared at runtime?

0 Answers  

---

when to use : in c program?

2 Answers  

---

void main(int n) { if(n==0) return; main(--n); printf("%d ",n); getch(); } how it work and what will be its output...............it any one know ans plz reply

0 Answers  

---

Why cd or dvd are round why not square.

1 Answers  

---

write a recursive program in'c'to find whether a given five digit number is a palindrome or not

2 Answers  

---

Why doesn't C support function overloading?

2 Answers  

---