Sams Teach Yourself C in 21 Days

Variables and Constants,” Table 3.1 presented the values typically stored in IBM-compat-

ible PCs. However, these values aren’t guaranteed.

The following rules apply to variable types:

• A character (char) is the smallest data type. A character variable (type char) will
  be one byte.


• A short variable (type short) will be smaller than or equal to an integer variable
  (typeint).


• An integer variable (type int) will be smaller than or equal to the size of a long
  variable (type long).


• An unsigned integer variable (type unsigned) is equal to the size of a signed inte-
  ger variable (type int).


• A float variable (type float) will be less than or equal to the size of a double vari-
  able (type double).
  Listing D.2 presents a commonly used way to print the size of the variables based on the
  machine on which the program is compiled.

LISTINGD.2 Printing the size of the data types

1: /*==========================================================*

2: * Program: listD02.c *

3: * Book: Teach Yourself C in 21 Days *

4: * Purpose: This program prints the sizes of the variable *

5: * types of the machine the program is compiled on *

6: *==========================================================*/

7: #include <stdio.h>

8: int main(void)

9: {

10: printf( “\nVariable Type Sizes” );

11: printf( “\n=========================” );

12: printf( “\nchar %d”, sizeof(char) );

13: printf( “\nshort %d”, sizeof(short) );

14: printf( “\nint %d”, sizeof(int) );

15: printf( “\nfloat %d”, sizeof(float) );

16: printf( “\ndouble %d”, sizeof(double) );

17:

18: printf( “\n\nunsigned char %d”, sizeof(unsigned char) );

19: printf( “\nunsigned short %d”, sizeof(unsigned short) );

20: printf( “\nunsigned int %d\n”, sizeof(unsigned int) );

21:

22: return 0;

23: }

802 Appendix D

INPUT

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