c programming

please explain with examples call by value and call by pointers?
explain how the pointers arithmatics takes place.Alloc.h and type.h
have what functions?
Who is Participating?
in call by value you pass a copy of a value to a function, like

void F(int i) // i is a copy of a value passed.
   i = 5; // changes copy of value passed.

int main()
   int x = 1;
   F(x);  // does not change x.

In call by reference, a reference or pointer to the specified value is passed This reference may be used to change the actual value that was specified

void F(int *iptr) // Pointer to an int is passed.
   *i = 5; // changes value of caller's int.

int main()
   int x = 1;
   F(&x);  // Changes x.
mohua_banerjeeAuthor Commented:
thank  you for your cooperation
mohua_banerjeeAuthor Commented:
sir,i have not got all thE answer.if possible,please answer others.
Cloud Class® Course: Amazon Web Services - Basic

Are you thinking about creating an Amazon Web Services account for your business? Not sure where to start? In this course you’ll get an overview of the history of AWS and take a tour of their user interface.

I don't know what

>> explain how the pointers arithmatics takes
>> place.Alloc.h and type.h
>> have what functions?

means.  It doesn't make sense.

Also EE rules do state that you should only ask 1 question per EE question.   They also recommend a 50 point value for an easy question, 20 points for 2 questions is too little. I will answer the 2nd question--if you can explain it, but in the future try to ask only 1 question at a time and assign them fair point values.
I haven't a clue what you mean in the 2nd part of the question.

A note on pinter arithmetic though,
is that you can subtract pointers to
find out how much space between them

char *p1, *p2;
p1 = "My String"
p2 = p1 + 3;

//p2 - p1 == 3
//p1 = "My String"
//p2 = "String"

//Because p1 is a pointer to char
//the following moves the address of
//p1 up 3 chars (bytes)

//NB The above operation is dependent
//on type. Therefore:
int* p3;
int test[]={1,2,3,4};
p3 = &test;

//The following makes *p3 == 2
//even though an int take up 2 bytes
//memory. The compiler works this out
//automatically for you

As for alloc.h, these functions
are for dynamically creating memory
on the heap.
   You offered a very low point value for this question, then when I answered it, you gave me a bad grade too!  You should only give a low grade if the answer is incorrect.  My answer was not incorrect.  If you don't understand the answer you can ask for clarification, but to simply grade a question with a low grade for no reason is not fair.
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.