How to call a function in another function for C++?

Question

Hello everyone, I'm trying to call a function from another but I don't think i'm doing it correctly. Here is my code:

int numOfNodes(struct listNode * firstNode){
int countNodes = 0;
while(firstNode -> next != NULL){
countNodes ++;
}
return countNodes + 1;
}

int middleOfList(struct listNode * firstNode){
int count = 0;
** while(count != numOfNodes(struct listNode * firstNode) / 2) {
** if (count = (numOfNodes(struct listNode * firstNode)/2) - 1){
int previous = firstNode -> num;
firstNode -> next;
count++;
}
else{
firstNode -> next;
count++;
}
}
** if(numOfNodes(struct listNode * firstNode) % 2 != 0) {
return firstNode -> next -> num;
}
else {
int total = ((firstNode -> next -> num) + previous) / 2 ;
return total;
}
}

I'm trying to call numOfNodes in middleOfList but keep getting the error:
"error: expected primary-expression before 'struct'" The error occurs where you see ** in my middleOfList function. All answers are appreciated and thank you in advanced.

Answer 1

Try to call `numOfNodes` like this

numOfNodes(firstNode)

As I understand it, argument type is not needed on call, only the argument is (cmiiw).

Answer 2

Lpang is correct, you are declaring the functions signature instead of calling it. Additionally as a side note, you do not need the struct keyword in the function signature. In C it is required but in C++ you dont have to do this.

In C:

struct Thing{};

Is created and used in functions like:

struct Thing t;

But this is cumbersome so you can do this:

typedef struct {} Thing;

Use:

Thing t;

In C++:

struct Thing{};

is equivalent to the typdef version in C, so you can just refer to the type as the name of the struct. This is more C++ like