Review: difference in behavior between C and Java in the assignment statement

Java will only allow "safe" assignments for number data types:

int x; double y; Allowed: y = x; Not allowed (without casting): x = y; // Need: x = (int) y;

In contrast, C is always allow assignment of any number type value

int x; double y; Allowed: y = x; x = y; // Without casting !

Difference in behavior between C and Java in function invocations using mismatched types

The same behavior applies when you invoke a function using values of different data type than specified in the function signature:

Java will allow a function call if:
The data type of the actual parameter can safely be converted to the data type of the formal parameter
C will always allow the function call
But remember that:
C will convert the actual parameter to the data type of the formal parameter if they are different number types

Example function calls that shows the difference between C and Java

The following C program will compile and run without casting:

int square(int x) { return x*x; } int main( ) { float a = 4, b; b = square(a); // C compiler will convert (float) a to (int) ! printf("Square of %f = %f\n", a, b); }

DEMO: demo/C/set1/param1.c

Example function calls that shows the difference between C and Java

A same program in Java will have compile errors:

public class param1 { public static int square(int x) { return x*x; } public static void main(String[] args) { float a = 4, b; b = square(a); // Cannot pass a float value ! Need (int) casting System.out.printf("Square of %d = %d\n", a, b); } }

Java requires casting (int) !

DEMO: demo/C/set1/param1.java