C Programming - Functions - Discussion

Function returns values even in following two cases.

1) return a, return b;

2) return (2, 4);

If function return more then one value to only one L value then right argument will be taken,

Ex:
a=func();

And,
func{
-----------
-------
return (c,b);
}

Then a==b.

Explanation:

Step 1: int i=3, j=4, k, l; The variables i, j, k, l are declared as an integer type and variable i, j are initialized to 3, 4 respectively.

The function addmult(i, j); accept 2 integer parameters.

Step 2: k = addmult(i, j); becomes k = addmult(3, 4)

In the function addmult(). The variable kk, ll are declared as an integer type int kk, ll;

kk = ii + jj; becomes kk = 3 + 4 Now the kk value is '7'.

ll = ii * jj; becomes ll = 3 * 4 Now the ll value is '12'.

return(kk, ll); It returns the value of variable ll only.

The value 12 is stored in variable 'k'.

Step 3: l = addmult(i, j); becomes l = addmult(3, 4)

kk = ii + jj; becomes kk = 3 + 4 Now the kk value is '7'.

ll = ii * jj; becomes ll = 3 * 4 Now the ll value is '12'.

return(kk, ll); It returns the value of variable ll only.

The value 12 is stored in variable 'l'.

Step 4: printf("%d, %d\n", k, l); It prints the value of k and l.

Hence the output is - 12, 12

I think the answer should be compile error. Because the function return two values at a time which is not possible.

Can anyone explain me the concept ?

LL is only returning values for both variables because KK is being overwritten by LL.

Had there been only "kk" being returned 'addmult()' would return only '7'
but since two different computations are being returned the greater value (i.e. 12)is overriding the smaller value(i.e. 7) and so the result of the both the computations stored in k and l respectively are turning out be 12.

The return function to return only one value.
Return(x); is true.
Return (x,y) is false it error.

In the return statement if there is more than one argument, it will the rightmost argument value will be sent to the calling function.

In this program we have return(kk,ll) the rightmost argument here is ll, in the definition ll is assigned to multiplication of the two variables only i.e " 3*4 =12".

Thank you @sundar. But how to differentiate comma and comma opertor. Where are the comma operators necessary. Can you please explain me.

@Prashanthi.

It depend on whether you are changing the value in called function or not if you are catching value of I and j through pointer or address and if you are doing any operation in called function then sure the original value of I and j get changed.