CODEWITHSUNDEEP
c++
Ivan Erlic
Ivan Erlic

Reputation: 391

C++ Passing Pointer To A Function

I have a problem passing a pointer to a function. Here is the code.

#include <iostream>

using namespace std;

int age = 14;
int weight = 66;

int SetAge(int &rAge);
int SetWeight(int *pWeight);

int main()
{
    int &rAge = age;
    int *pWeight = &weight;

    cout << "I am " << rAge << " years old." << endl;   
    cout << "And I am " << *pWeight << " kg." << endl;

    cout << "Next year I will be " << SetAge(rAge) << " years old." << endl;
    cout << "And after a big meal I will be " << SetWeight(*pWeight);
    cout << " kg." << endl;
    return 0;
}

int SetAge(int &rAge) 
{
    rAge++;
    return rAge;
}

int SetWeight(int *pWeight)
{
    *pWeight++;
    return *pWeight;
}

My compiler outputs this:

|| C:\Users\Ivan\Desktop\Exercise01.cpp: In function 'int main()':
Exercise01.cpp|20 col 65 error| invalid conversion from 'int' to 'int*' [-fpermissive]
||   cout << "And after a big meal I will be " << SetWeight(*pWeight);
||                                                                  ^
Exercise01.cpp|9 col 5 error| initializing argument 1 of 'int SetWeight(int*)'    [-fpermissive]
||  int SetWeight(int *pWeight);
||      ^

PS: In real life I wouldnt use this but I got into it and I wanna get it working this way.

Upvotes: 0

Views: 105

Answers (4)

Luca
Luca

Reputation: 595

The * symbol can have two different meanings in C++. When used in a function header, they indicate that the variable being passed is a pointer. When used elsewhere in front of a pointer it indicates that to which the pointer is pointing. It seems you may have confused these.

Upvotes: 0

Ivan Erlic
Ivan Erlic

Reputation: 391

First I took your feedback and changed:

cout << "And after a big meal I will be " << SetWeight(*pWeight);
// to
cout << "And after a big meal I will be " << SetWeight(pWeight);

// But after that I changed also:
*pWeight++;
// to
*pWeight += 1;

Upvotes: 0

Moe
Moe

Reputation: 29725

You shouldn't dereference the pointer. It should be:

cout << "And after a big meal I will be " << SetWeight(pWeight);

Also, in SetWeight(), you are incrementing the pointer instead of incrementing the value, it should be:

int SetWeight(int *pWeight)
{
    (*pWeight)++;
    return *pWeight;
}

Upvotes: 5

Mac
Mac

Reputation: 14791

int *pWeight = &weight;

This declares pWeight as a pointer to an int. SetWeight actually takes a pointer to an int, so you can just pass pWeight straight in without any other qualifiers:

cout << "And after a big meal I will be " << SetWeight(pWeight);

Upvotes: 1

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