Question

Currently I’m using:

 int a=10;
 if(a=20)
     printf("TRUE");
 else
     printf("false");

Which prints, in C, the value TRUE.

But in case of java:

int a=10;
if(a=20)
    System.out.println("TRUE");
else
    System.out.println("FALSE");

I’ll get a compile time error about an incompatible type.

Answer 1

The reason for that is that in C there is no specific type boolean – instead any non-0 integer evaluates to a boolean “true”. Thus in your C code:

if(a=20)

a is assigned the value 20, which is non-0 – and the condition is evaluated as true

In java, there’s a fundamental type boolean and the value of the conditional inside if must be of this type.

a=20

in Java assigns 20 to a and returns the final result of evaluation as integer value 20, however type boolean is expected – hence you’re getting a compile-time error about the incompatible types.

If you want to do a comparison of a with 20, however, you need to use == operator both in C and Java:

if(a == 20)

This will compile in both C and Java and print FALSE in both languages.