The Fundamental Data Types

1. The Fundamental Data Types

2. Outline • Declarations, Expressions, and Assignment • The Fundamental Data Types • Characters and the data Type char • The data Type int • The Integral Types short, long, and unsigned • The Floating Type

3. Outline (continueb) • The Use of typedef • The sizeof Operator • The Use of getchar() anb putchar() functions • Mathematical Functions • Conversions and Casts • Hexadecimal and Octal Constants

4. beclarations, Expressions, anb Assignment • In C, all variables should be declareb at the beginning of the files, functions, and block. #include<stbio.h> int main(void) { int a , b, c; float x, y=3.3, z=-7.7; …

5. beclarations, Expressions, anb Assignment • In C, block is identified by a curly brace { } • declared variables are only valid within the scope or the block. • Expressions are meaningful combinations of constants, variable, operators, and function calls. • Most expression has a value

6. a+b; sqrt(7.33333); 5.0*x-tan(9.0/x); Expr can be assigned as a value to a variable expr = expr; b=(3.123*a+b); x=x+1;

7. The Fundamental Data Types • List of fundamental data type: char [signed] char unsigned char [signed ] short int [signed] int [signed] long int (short) (int) (long) unsigned short int unsigned int unsigned long int float double long double

8. The Fundamental Data Types • Commonly used list of fundamental data type: char signed char unsigned char short int long unsigned short unsigned unsigned long float double long double

9. Characters and the Data Type char • char can be used to hold small range of integer • char is interpreted as 1 byte (most machines, 1 byte is implemented as 8 bits) • Therefore, it has 28=256 combinations or can hold for 256 distinct values. • People use char (1 byte) to hold for alphabetic letters (lower and upper cases), digits, punctuations, and special characters such as % and +. • Most machines use ASCII character codes (see Append D)

10. 'a' 'b' 'c' … 'z' 97 98 99 … 122 'A' 'B' 'C' … 'Z' 65 67 68 … 90 '0' '1' '2' … '9' 48 49 50 … 57 a =A+32 b=B+32 … … z=Z+32 '&' '*' '+' 38 42 43

11. Characters and the Data Type char • Single quote (')is used to identify a individual character constant • Escape characters

12. Alert \a 7 Backslash \\ 92 Backspace \b 8 Carriage return \r 13 Double quote \" 34 Form-feed \f 12 Horizontal tab \t 9 New-line \n 10 Null character \0 0 Single quote \' 39 Vertical tab \v 11 Question mark \? 63

13. printf("%c", '\a'); printf("\"Book on C\" is published"); printf("\'Book on C\' is published"); Octal character expression: printf("%c", '\a'); printf("%c", '\007'); Printf("%c",'\07'); printf("%c", '\7'); But not printf("%c", '7');

14. char c='a'; printf("%c", c); print out character a printf("%b", c); print out 97 printf("c%c%c, c, c+1, c+2); print out a, b, c char c; int i; for (i='a'; i<='z';++i) print out abc…z printf("%c", i); for (c=65; c<=90;++c) print out ABC .. Z printf("%c", c); for (c='0'; c<='9';++c) print out 48, 48, …57 printf("%c", c);

15. Characters and the Data Type char • decimal digits 20753 2x104 + 0x103 +7x102 +5x101+3x100 dndn-1…d2d1d0 dnx10n + dn-1x10n-1 +dn-2x10n-2 +…+d2x102+d1x101 +d0x100

16. Characters and the Data Type char • binary digits (=64+32+1=97) 01100001 0x27 + 1x26 +1x25 +0x24 +0x23 +0x22 +0x21 +1x20 bnbn-1…b2b1b0 bnx2n + bn-1x2n-1 +bn-2x2n-2 +…+b2x22+b1x21 +b0x20

17. Characters and the Data Type char • The value range of char, signed char, and unsigned char (all 1 byte) • signed char (-128, 127) • unsigned char (0, 255) • char, either (-128, 127) or (0, 255) depending on compiler

18. The Data Type int • Implemented as either 2 bytes or 4 bytes For a 4 byte system, The total combination is 232 and the value range is -231, -231+1, … -3, -2, -1, 0, 1,2, 3, … 232-1 min max For a 2 byte system, The total combination is 216 and the value range is min -215, -215+1, … -3, -2, -1, 0, 1,2, 3, … 215-1 max

19. The Data Type int • For 4 byte systems • For 2 byte systems The min value is –231 = –2147483648 about 2 billion The max value is +231-1 = + 2147483647 The min value is –215 = –32768 about 32 thousands The max value is +215-1 = + 32767

20. The Data Type int • On any machines, we can define a big number #define BIG 2000000000 #define SMALL -2000000000 int main(void) { int a, b=BIG, c=BIG, d=SMALL, e=SMALL; a=b+c; /* out of range , or called overflow */ a=d+e; /* out of range, or called underflow */ …

21. The Integral Types short, long, and unsigned • Need long, if int is not enough to handle large value of integer • Need short, if we want to save storage space • The range of short and long depend on the implementation, 2 bytes or 4 bytes. • short (2 bytes) The min value is –215 = –32768 about 32 thousands The max value is +215-1 = + 32767

22. The Integral Types short, long, and unsigned • long (4 bytes) • unsigned The min value is –231 = –2147483648 about 2 billion The max value is +231-1 = + 2147483647 4 bytes: The min value is 0 and the max value is +232-1 = + 4294967295 (4 billion) 2 bytes: The min value is 0 and the max value is +216-1 = + 65535 (2 billion)

23. The Integral Types short, long, and unsigned • Suffix for literal integer Suffix type example u or U unsigned 37u u or L long 37L ul or UL unsigned long 37UL

24. The Floating Type • Suffix for floating-point numbers • Floating-point number is composed of three parts: integer, fraction, and exponent Suffix type example f or F float 3.7f l or L long double 3.7L

25. The Floating Type • Suffix for floating-point numbers • Floating-point number is composed of four parts: integer, decimal point, fraction, and exponent Suffix type example f or F float 3.7f l or L long double 3.7L 33.777e-22

26. The Floating Type • examples 3.14158 314.149e-2f 0e0 1. Not 3.14,159 314159 .e0 -3.14159

27. The Floating Type • Storage of floating-point variable • float holds 4 bytes • double holds 8 bytes • Precision: describe the nunber of significant decimal places • Range: describe the limitation of floating –point value, the type of variable can hold

28. The Floating Type • float has 10-38 to 10+38 • double has 10-308 to 10+308

29. The Use of typedef • typedef allows programmer to explicitly redefine the identifier of data type • The purpose of introducing typedef is • Abbreviating long declaration • Make portable code by voiding different platform implementation of type size

30. The Use of typedef • Example: typedef char uppercase; typedef int INCHES, FEET; typedef unsigned long size_t; uppercase u; INCHES length, width;

31. The sizeof Operator • In C, sizeof() can be used to find out the details about the implementation of data type • Since the different platform implement data type differently, the results should be different.

32. The sizeof Operator • Standard: sizeof(char)=1 sizeof(char)<=sizeof(short)<=sizeof(int)<=sizeof(long) sizeof(signed)=sizeof(unsigned)=sizeof(int) sizeof(float)<=sizeof(double)<=sizeof(long double)

33. /* Compute the size of some fundamental types. */ #include <stdio.h> int main(void) { printf("The size of some fundamental types is computed.\n\n"); printf(" char:%3d byte \n", sizeof(char)); printf(" short:%3d bytes\n", sizeof(short)); printf(" int:%3d bytes\n", sizeof(int)); printf(" long:%3d bytes\n", sizeof(long)); printf(" unsigned:%3d bytes\n", sizeof(unsigned)); printf(" float:%3d bytes\n", sizeof(float)); printf(" double:%3d bytes\n", sizeof(double)); printf("long double:%3d bytes\n", sizeof(long double)); return 0; }

34. The size of some fundamental types is computed. char: 1 byte short: 2 bytes int: 4 bytes long: 4 bytes unsigned: 4 bytes float: 4 bytes double: 8 bytes long double: 16 bytes

35. The Use of getchar() anb putchar() • Besides of printf() and scanf() functions, you can use getchar() and putchar() to input characters from keyboard and output characters on screen. • Example:

36. #include <stdio.h> int main(void) { int c; while ((c = getchar()) != EOF) { putchar(c); putchar(c); } return 0; } -1, read to the end of file or CTR-C I would like to learn C. II wwoouulldd lliikkee ttoo lleeaarrnn CC..

37. The Use of getchar() anb putchar() • Alphabetic letters either in lowercase or in uppercase are all in a range, as specified in ASCII code. • Therefore, you can use >='a' && <='z' (>=97 && <=122) to check the character is in the range of lowercase >=65 && <=90 to check the character is in the range of uppercase

38. #include <stdio.h> int main(void) { int c; while ((c = getchar()) != EOF) if (c >= 'a' && c <= 'z') putchar(c + 'A' - 'a'); else putchar(c); return 0; }

39. Mathematical Functions • There is a standard mathematical functions built in the math.h library, such as sqrt(), pow(), exp(), log(), sin(), cos(), tan(), … • You can find out math functions by reading the math.h file • In UNIX, you need to link math.h while submitting compilation command, using Cc Cfile.c -lm

40. #include <math.h> #include <stdio.h> int main(void) { double x; printf("\n%s\n%s\n%s\n\n", "The square root of x and x raised", "to the x power will be computed.", "---");

41. while (1) { /* do it forever, endless loop */ printf("Input x: "); scanf("%lf", &x); if (x >= 0.0) printf("\n%15s%22.15e\n%15s%22.15e\n%15s%22.15e\n\n", "x = ", x, "sqrt(x) = ", sqrt(x), "pow(x, x) = ", pow(x, x)); else printf("\nSorry, your number must be nonnegative.\n\n"); } return 0; }

42. Result: The square root of x and x raised to the x power will be computed. --- Input x: 3 x = 3.000000000000000e+00 sqrt(x) = 1.732050807568877e+00 pow(x, x) = 2.700000000000000e+01

43. Input x: 2 x = 2.000000000000000e+00 sqrt(x) = 1.414213562373095e+00 pow(x, x) = 4.000000000000000e+00 Input x: -1 Sorry, your number must be nonnegative. Input x: 0 x = 0.000000000000000e+00 sqrt(x) = 0.000000000000000e+00 pow(x, x) = 1.000000000000000e+00 Input x: ^C

44. Mathematical Functions • Use abs() to obtain an absolute value of an integer, and fabs() to obtain an absolute value of a floating-point number

45. Conversions and Casts • For an expression which has mixed data type, what we expected. • Integral Promotions Store 65 to c Convert to char, while using %c char c='A'; printf("%c\n",c);

46. Conversions and Casts • In arithmetic expression, automatic conversion occurs char c; short s; int i; long l; unsighed u; unsigned long ul; float f; double d; long double ld; c-s/i return int u*7-i return unsigned u*2.0-i return double f*7-i return float

47. Conversions and Casts c+3 return int 7*s*ul return unsigned long c+5.0 return double ld+c return long double d+s return double u-ul return unsigned long s*i/l return long u-l return system-dependent

48. Conversions and Casts • Casting (explicitly converting) (double) i Do not change the type of variable i; It just generates a double value based on the value of I; Example: if i is 4, it generates 4.0 l=(long) ('A'+1.0) f=(float) ((int)d+1); d=(double) i/3; d=(double) (x=77);

49. Hexadecimal and Octal Constants • Based on base of 16 Hexadecimal digit: 0 1 2 3 4 5 6 7 8 9 A B C D E F Decimal digit: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 hnhn-1…h2h1h0 hnx16n + hn-1x16n-1 +hn-2x16n-2 +…+h2x162+h1x161 +h0x160

50. Hexadecimal and Octal Constants • Example A0F3C = Ax164 + 0x163 +Fx162 +3x161+Cx160 =659260