CODEWITHSUNDEEP
c++syntax
Lost_DM
Lost_DM

Reputation: 951

Silly syntax error c++

I'm completely new to C++.

Bashing my head against this error for over an hour. Probably someone with experience can see right through it.

The following code gives an error:

class TimeTravellingCellar { 

private:

public:
  int determineProfit (int [] profit, int [] decay) { 
    int N = sizeof(profit)/sizeof(decay); 
    int max = 0; 
    for (int i = 0; i < N; i++) { 
      for (int j = 0; j < N; j++) { 
        if (i == j) continue; 
        if (profit [i] - decay [j] > max) 
          max = profit [i] - decay [j]; 
      } 
    } 
    return max; 
  } 
}

Visual Studio Express puts a red line under profit in the parameters of determineProfit and says:

expected a ')' before identifier profit.

I will appreciate some help. Thanks!

Upvotes: 2

Views: 438

Answers (7)

Ed Swangren
Ed Swangren

Reputation: 124642

You are declaring your arrays as if this were c#. It should be 

int profit[]

Or

int *profit

You'll hit this one next. You need to terminate your class with a semi-colon.

class Foo { 

};  <----

The next problem you have is logical, not syntactic. This does not do what you think it does:

int N = sizeof(profit)/sizeof(decay);

You are taking the sizeof two pointers, not the size of the arrays. You actually have:

int N = 4/4  /* assumes sizeof int == 4 */

You need to pass in the size of your to the function as well (or, better yet; stop using arrays and use a vector<T>.)

When you take an "array" as an argument to your function it actually decays to a pointer to the array type (an array proper cannot be passed to a function). So it follows that:

void Foo( int array[] ) {
    size_t arrSize = sizeof(array);
    // arrSize == 4 for a 32-bit system, i.e., sizeof(int*)

    int a[100];
    size_t actualSizeInBytes = sizeof(a);
    // actualSizeInBytes == 400, i.e., 4 * 100 as an int occupies 4 bytes
}

Next, this line causes your first iteration to always be skipped. Not sure if that is intentional:

if (i == j) continue;

Upvotes: 12

rajA
rajA

Reputation: 1

int determineProfit (int[] profit int [] decay

here is your error - the above statement is wrong; it should be like this

int determineProfit (int profit[], int decay[])

Upvotes: 0

jli
jli

Reputation: 6623

You don't declare arrays like that in C++, the [] needs to go after the name. Also note you need to have a semicolon after the class declaration.

class TimeTravellingCellar { 

private:

public:
  int determineProfit (int profit[], int decay[]) { 
    int N = sizeof(profit)/sizeof(decay); 
    int max = 0; 
    for (int i = 0; i < N; i++) { 
      for (int j = 0; j < N; j++) { 
        if (i == j) continue; 
        if (profit [i] - decay [j] > max) 
          max = profit [i] - decay [j]; 
      } 
    } 
    return max; 
  } 
};

Edit: also remember that sizeof(pointer) will return the number of bytes of the pointer type, not the number of elements in the array. So if you have an int array, sizeof(array) == sizeof(int). Your N value will always equal 1.

Upvotes: 3

John Humphreys
John Humphreys

Reputation: 39284

This line is wrong:

 int determineProfit (int [] profit, int [] decay) {

Change it into:

int determineProfit (int profit[], int decay[]) {

or

int determineProfit (int* profit, int* decay) {

and add a closing ;

If you do that and add a main, of course:

int main() {}

then you can compile your code - I just tried it with g++.

Upvotes: 2

themel
themel

Reputation: 8895

A tutorial on arrays in C may be enlightening, especially as regards the passing of array parameters.

Upvotes: 0

Chris Smith
Chris Smith

Reputation: 5454

Brackets are associated with the variable name, not the type. The first line should be

int determineProfit (int profit[], int decay[]) {

Upvotes: 0

Basile Starynkevitch
Basile Starynkevitch

Reputation: 1

Try int determineProfit (int* profit, int* decay) because for formal arguments, arrays and pointers are almost alike.

Upvotes: 1

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