CODEWITHSUNDEEP
cmutable
Shubham S. Naik
Shubham S. Naik

Reputation: 341

Does C has concept of mutable and immutable values of variables like Python?

#include<stdio.h>
int main(void)
{
        int x,y;
        x=10;
        y=x;
        x=5;
        printf("x=%d,y=%d\n",x,y);
        return 0;
}

Output: x=5,y=10

So can we say that y is immutable?

Upvotes: 0

Views: 1233

Answers (2)

msc
msc

Reputation: 34638

Except const, all the variables values are mutable in C.

So can we say that y is immutable?

The short answer: No.

Upvotes: 1

paxdiablo
paxdiablo

Reputation: 882048

So can we say that y is immutable?

We can, but we'd be wrong :-)

You only have to experiment a little to find this out. A simple y = 42 would suggest that y were not immutable but there is still some doubt in that it may have created a new value and pointed y at that, leaving the old value untouched.

This can be discounted with code like:

int y = 7;        // we have a y
int *pY = &y;     // and a pointer to it
y = 42;           // change y
printf ("%d %d\n", y, *pY);

You'll see there that both methods used to access y get the new value, indicating that the underlying value of y itself has changed, rather than having a new value created and y somehow redirected to it.

That's not to say C itself doesn't have immutable data, that's really what the const keyword is all about. However, that's rather different to Python's concept of immutability.

Upvotes: 0

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