Is there any Difference

[caradoc]

Consider declaring variables and using then for computation in C++ program as below in Method 1 and Method 2

Method 1:
int a, b, c;
a=b+c;

Method 2:
int b, c;
int a=b+c;

Though on the user interface side both gives the same result I have a doubt in this. Is there any difference in the working of Method 1 and Method 2 internally or will it get assigned and evaluated internally also in the same way. Kindly explain me.

[ashlee]

Yes there is clearly a distinction between the internal working of Method 1 and Method2.Methdo2 is always preferred than Method1 when you understand the internal working of both methods. In method1 the expression b+c is evaluated and is stored in a temporary object of type int and then only it is assigned to integer variable named as a. After assigning the value of b+c integer variable a, the temporary object gets destroyed. In contrast in method 2 the value of b+c is calculated and directly assigned to integer variable a without the use of temporary variable. So performance wise method2 is always better than method1.

[hvg_99]

Method 1:
int a, b, c;
a=b+c;

Method 2:
int b, c;
int a=b+c;

In the first case we are declaring 3 variables and next step we are adding two values and assigning it to 'a';

Whereas in the second case we are declaring two variables by name 'b' and 'c' and in the next step we are declaring a variable by name 'a' and immediately assigning sum of b and c. so we are minimizing the declaration line.

In the first case 3 variables are getting declared and then the expression.

I hope i have cleared your doubt.

Regards,
Gayatri