What does the prototype "const int* foo(int)" mean,especially in contrast to "int* foo(int)"?I understand the second only

Question

I know that int* foo(int) prototype means that foo is a function that takes an integer argument and returns a pointer to an integer.But what does the following mean?

  const int* foo(int);

I tried to reason but failed.My book doesn't say anything about this but I see stuff like this in library function prototypes.So please tell me what it means.

1. You haven't googled `const keyword C`, have you? 2. http://cdecl.org — , May 14 '13 at 13:51
The same, except that you aren't allowed to change what `foo`'s result points to. — Daniel Fischer, May 14 '13 at 13:52
do you have any counter question, I believe links provided to are sufficient, let me know you have other doubts — Grijesh Chauhan, May 14 '13 at 14:20

Grijesh Chauhan · Accepted Answer · 2013-05-14T14:05:12.457

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So that value pointed by returned address can't be change via address (useful when foo() returns address of const).

const int* p2c =  foo(int);
*p2c=10;  <-- "error"

edited May 14 '13 at 14:05

answered May 14 '13 at 13:52

Grijesh Chauhan

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Not quite true--You _can_ change the returned value (the pointer) -- you just can't change what it points to. – Wayne Conrad May 14 '13 at 14:02

score 1 · Answer 2 · answered May 14 '13 at 13:53

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from cdecl:

this means

declare foo as function (int) returning pointer to const int

answered May 14 '13 at 13:53

MOHAMED

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score 1 · Answer 3 · answered May 14 '13 at 13:53

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const int* foo(int);

foo is a function that takes an integer argument and returns a pointer to an const integer.It means you are allowed to change pointer but not it's value.

answered May 14 '13 at 13:53

Dayal rai

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What does the prototype "const int* foo(int)" mean,especially in contrast to "int* foo(int)"?I understand the second only

3 Answers3