CODEWITHSUNDEEP
cpointers
user2970691
user2970691

Reputation: 55

The difference between int(*function)(int,int) and int*function(int,int)

I am studying pointers of C and from the book of Deitel I don't get the difference between int(*function)(int,int) and int*function(int,int) when the function is expressed.

Upvotes: 1

Views: 10928

Answers (3)

sqykly
sqykly

Reputation: 1586

Rule of thumb for reading types in C:

  1. Starting with the identifier you're defining

    • in int(*function)(int,int), "function is a..."

    • in int*function(int,int), "function is a..."

  2. Read to the right until you hit the end of the line or a closing parenthesis

    • in int(*function)(int,int), you hit the parenthesis immediately.

    • in int*function(int,int), "... function that takes two parameters of type int and int..."

  3. Read left from where you started

    • in int(*function)(int,int), "... pointer to ..."

    • in int*function(int,int), "... that returns a pointer to int."

  4. If you stopped because you hit a closing parenthesis, follow steps 2 & 3 again starting with the closing parenthesis and returning to its corresponding opening parenthesis.

    • in int(*function)(int,int) we only read (*function) so far, so we continue: "... function that takes parameters of type int and int..." and backing up, "... that returns an int"

    • we hit the end of the line in the other one.

Putting it all together:

int(*function)(int,int)

function is a pointer to a function that takes two arguments of type int and int that returns an int

int*function(int,int)

function is a function that takes two arguments of type int and int and returns a pointer to int.

Upvotes: 7

user1744056
user1744056

Reputation:

The first one is a pointer to function which received two int arguments and the second one is just a function which returns pointer to int and receives two int arguments. It is two really different programming entities. First is data type second is code (function).

Upvotes: 3

piokuc
piokuc

Reputation: 26184

The first is a pointer to a function which returns int. The second is a declaration of a function which returns a pointer to int.

Upvotes: 2

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