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Join Date: Aug 2004
Location: Minnesota
Posts: 18
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Newbie Poster
New to C++ Pointers and need help with identifying where the errors are I am stuck on this problem..you are supposed to locate the error in the segment of code:
char var1, ptr1;
var1='X';
ptr1=&var1;
Can someone please help me figure this out. It is much appreciated.
char var1, ptr1;
var1='X';
ptr1=&var1;
Can someone please help me figure this out. It is much appreciated.
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Join Date: Aug 2004
Location: Minnesota
Posts: 18
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Rep Power: 5
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Newbie Poster
[quote=hfick]I am stuck on this problem..you are supposed to locate the error in the segment of code:
char var1, ptr1;
var1='X';
ptr1=&var1;
Can someone please help me figure this out. It is much appreciated.
I think their needs to be an * by the ptr1 where the variable is declared but I am really not sure.??
char var1, ptr1;
var1='X';
ptr1=&var1;
Can someone please help me figure this out. It is much appreciated.
I think their needs to be an * by the ptr1 where the variable is declared but I am really not sure.??
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Join Date: Aug 2004
Location: Hanover
Posts: 152
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Junior Poster
char var1, *ptr1; // <--- * goes here var1='X'; ptr1=&var1;
It's important to remember that you need '*' for each pointer variable. Therefore: char* ptr1, ptr2; doesn't work as intended.
For two ptrs, you must do char *ptr1, *ptr2.
Ed
[quote=hfick]
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Originally Posted by hfick
I am stuck on this problem..you are supposed to locate the error in the segment of code:
char var1, ptr1;
var1='X';
ptr1=&var1;
Can someone please help me figure this out. It is much appreciated.
I think their needs to be an * by the ptr1 where the variable is declared but I am really not sure.??
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In a world without walls or fences,
What use are Windows and Gates.
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Join Date: Aug 2004
Location: Minnesota
Posts: 18
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Rep Power: 5
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Newbie Poster
Thank you very much
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Join Date: Aug 2004
Location: Minnesota
Posts: 18
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Rep Power: 5
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Newbie Poster
That is what I thought for the one above...But I am stuck again on this one..could you possibly help again?
char c='A';
char *p;
p=c
* goes here right?? char *c='A';
char *p;
p=c;
hopefully i am getting this..please let me know if this is right
char c='A';
char *p;
p=c
* goes here right?? char *c='A';
char *p;
p=c;
hopefully i am getting this..please let me know if this is right
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Join Date: Aug 2004
Location: Hanover
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Junior Poster
char c='A'; char *p; p=&c // <-- should read a pointer (*) to char named p gets the the address (&) of char c
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In a world without walls or fences,
What use are Windows and Gates.
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Join Date: Aug 2004
Location: Minnesota
Posts: 18
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Newbie Poster
thank you..you must really get this stuff..must be nice...could you help me some more...
var1's address is 55441
int var1=2323;
int *ptr;
ptr=&var1;
var1=?
ptr=?
*ptr=?
var1's address is 55441
int var1=2323;
int *ptr;
ptr=&var1;
var1=?
ptr=?
*ptr=?
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Join Date: Jul 2004
Location: India
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Newbie Poster
var1's address is 55441
int var1=2323;
int *ptr;
ptr=&var1;
var1 = 2323
ptr = 55441
*ptr = 2323
int var1=2323;
int *ptr;
ptr=&var1;
var1 = 2323
ptr = 55441
*ptr = 2323
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Join Date: Aug 2004
Location: Minnesota
Posts: 18
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Newbie Poster
Thank you shalin....THat is what I thought but wasn't for sure...
THis one wants to know what the output produced is when the code is executed:
char var1 = 's';
char var2 = 'x';
char *ptr1, *ptr2;
ptr1=&var1;
ptr2=&var2;
*ptr2=*ptr1;
cout << *ptr1 << " " << var2 << endl;
THis one wants to know what the output produced is when the code is executed:
char var1 = 's';
char var2 = 'x';
char *ptr1, *ptr2;
ptr1=&var1;
ptr2=&var2;
*ptr2=*ptr1;
cout << *ptr1 << " " << var2 << endl;
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Join Date: May 2004
Posts: 251
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Posting Whiz in Training
Try to understand the concept of pointers rather.It's simple actually.A pointer points to the address in memory of a variable.That way if you change one, the changes can be seen at all places.Multiple pointer can point to a variable.
A var can be tought of as a TV and the pointer a Remote Control.Change the channel anywhere,the result is on the TV.And a TV can have multiple remotes
Look below:
&val means address of the variable var
*p (if is a pointer (int *p; )) means value at address pointed at by p.Changes this will change the variable it points to.
int val = 1;
p=&val;
val+=10
cout<<val<<" *p="<<*p; //output is the same for both
(*p) += 4; //changes the value of val
cout<<val<<" *p="<<*p; //output is the same for both
The outputs are:
11 11
15 15
*(p++) increses the address to which it points to by the pointers datatype size.
*(p)++ increses the val at the address pointed by p by 1.
Understand the pointer concept ?
A var can be tought of as a TV and the pointer a Remote Control.Change the channel anywhere,the result is on the TV.And a TV can have multiple remotes
Look below:
&val means address of the variable var
*p (if is a pointer (int *p; )) means value at address pointed at by p.Changes this will change the variable it points to.
int val = 1;
p=&val;
val+=10
cout<<val<<" *p="<<*p; //output is the same for both
(*p) += 4; //changes the value of val
cout<<val<<" *p="<<*p; //output is the same for both
The outputs are:
11 11
15 15
*(p++) increses the address to which it points to by the pointers datatype size.
*(p)++ increses the val at the address pointed by p by 1.
Understand the pointer concept
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