Sams Teach Yourself C in 21 Days

Object-Oriented Programming Languages 633

33: { BD1

34: printf(“\n”);

35:

36: for ( yctr = 0; yctr < bottomleftY - topleftY; yctr++ )

37: {

38: printf(“*”);

39: }

40: }

41: }

42:

43: int main(int argc, char* argv[])

44: {

45: int pt_x1 = 0, pt_y1 = 0;

46: int pt_x2 = 5, pt_y2 = 5;

47: int pt_x3 = 0, pt_y3 = 0;

48: long side = 4;

49:

50: // Call the square function two different ways

51: square( pt_x1, pt_y1, pt_x2, pt_y2);

52:

53: printf(“\n\n”); //put blank lines between squares

54:

55: square( pt_x3, pt_y3, side);

56:

57: return 0;

58: }

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If you try to compile this listing as C, it will generate an error. If you compile it

as a C++ program, it will work. As you can see, this listing has two functions

with the same name (see lines 7 and 25). You can also see in lines 51 and 55 that the

square()function is called in two different ways. You learned earlier in this book that

this is not correct in a C program. In an object-oriented program, this is acceptable. This

is polymorphism in action. When the square function is called, the program determines

which is the appropriate one to use. With a C++ program, the programmer does not need

to worry about which is correct.

LISTINGB1.1 continued

OUTPUT

ANALYSIS

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