Getting different results when dereferencing a pointer to an integer

Question

#include<stdlib.h>
#include<iostream>

using namespace std;

void fun(int* a){
    int b=*a++;
    cout<<b<<endl;
}
void fun1(int *a){
    int b=*a+1;
    cout<<b<<endl;
}
int main(){
    int n=5;
    fun(&n);//output remains 5
    fun1(&n);//output incremented by 1
}

In the function fun the value of n does not get incremented when done as shown in the above code, on the other hand in function fun1 the value of n gets incremented by 1.What is the problem with the first approach to increment n?

@walnut yeah thanks a lot ..your mentioned post cleared my doubt. — AADETYA JAISWAL, Jan 25 '20 at 21:33
@Maestro that won't do. You need preincrement `int b = ++*a;` — Aykhan Hagverdili, Jan 25 '20 at 21:34
@Maestro, int b=(*a)++ translates to use the value at which the pointer is pointing and then increment it. — AADETYA JAISWAL, Jan 25 '20 at 21:37

Yuki · Answer 1 · 2020-01-25T22:07:13.250

0

The behavior you observe is expected by the operator precendence rules.

In the first case it is a++, the previous value of a dereferenced.

In the second: the value of a dereferenced plus 1.

edited Jan 25 '20 at 22:07

answered Jan 25 '20 at 21:25

Yuki

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Getting different results when dereferencing a pointer to an integer

1 Answers1