Fundamental data types

1. Fundamental data types Chapter 3 in ABC

2. #include <stdio.h> • int main(void) • { • int a, b, c; • float x = 0.0f, y = 3.3f, z = -7.7f; • printf( “Input two integers: ” ); • scanf( “%d%d”, &b, &c ); • a = b + c; • x = y + z; • return 0; • } Declaration Declaration with initialization always initialize!!! Function calls Assignment statements

3. Fundamental data types • Integral (signed or unsigned) • char • short • int • long • Floating point types • float • double

4. Fundamental Data Types • Long form • charsigned charunsigned char • signed short int signed int signed long int • unsigned short int unsigned int unsigned long int • floatdoublelong double • Common (short) form • char signed char unsigned char • short int long • unsigned short unsigned unsigned long • float double long double

5. Functionality Groups • Integral Types: • char signed char unsigned char • short int long • unsigned short unsigned unsigned long • Floating Types: • float double long double • Arithmetic Types: • integral types • floating types

6. Constants

7. Some Character Constants and their Integer Values • character: 'a' 'b' 'c' ... 'z' • integer value: 97 98 99 ... 112 • character: 'A' 'B' 'C' ... 'Z' • integer value: 65 66 67 ... 90 • character: '0' '1' '2' ... '9' • integer value: 48 49 50 ... 57 • character: '&' '*' '+' • integer value: 38 42 43 The character ‘0‘ has a value of 48

8. Some Character Constants and their Integer Values The character ‘\0‘ has a value of 0

9. Some Character Constants and their Integer Values • char c = 'a'; • printf("%c", c); • printf("%d", c); • printf("%c%c%c", c, c+1, c+2); a is printed 97 is printed abc is printed

10. Some Character Constants and their Integer Values • character: 'A' 'B' 'C' ... 'Z' • integer value: 65 66 67 ... 90 • char c = 0; • int i = 0; • for ( i = 'a'; i <= 'z'; ++i ) • printf( “%c”, i ); • for ( c = 65; c <= 90; ++c ) • printf( “%c”, c ); • for ( c = '0'; c <= '9'; ++c ) • printf( “%d”, c ); abc ... z is printed ABC ... Z is printed 484950 ... 57 is printed

11. User Defined Constants • #include <stdio.h> • int main(void) • { • int c = 0; • while ( ( c = getchar() ) != EOF ) • { • putchar( c ); • putchar( c ); • } • return 0; • } Loop until the End Of the File in stdio.h appear the line: #define EOF (-1)

12. Constants

13. Decimal, Hexadecimal, Octal conversions • #include <stdio.h> • int main(void) • { • printf( “%d %x %o\n”, 19, 19, 19 ); • printf( “%d %x %o\n”, 0x1c, 0x1c, 0x1c); • printf( “%d %x %o\n”, 017, 017, 017); • printf( “%d\n”, 11 + 0x11 + 011); • printf( “%x\n”, 2097151); • printf( “%d\n”, 0x1FfFFf); • return 0; • } 19 13 23 28 1c 34 15 f 17 37 1fffff 2097151

14. compute the size of some fundamental types sizeof returns the number of bytes reserved for a variable type. • #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; • }

15. compute the size of some fundamental types • run on “PC Pentium 3": • 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: 8 bytes what is the output of the program on nova?

16. compute the size of some fundamental types • sizeof(char) == 1 • sizeof(short) <= sizeof(int) <= sizeof(long) • sizeof(signed) == sizeof(unsigned) == sizeof(int) • sizeof(float) <= sizeof(double) <= sizeof(long double)

17. Going over the Limit • #include <stdio.h> • #include <limits.h> • int main( void ) • { • int i = 0; • unsigned u = UINT_MAX; • for ( i = 0; i < 5; ++i ) • printf( "%u + %d = %u\n", u, i, u + i ); • for ( i = 0; i < 5; ++i ) • printf( "%u * %d = %u\n", u, i, u * i ); • return 0; • } Typically equal to 0xFFFFFFFF == 232-1 == 4294967295

18. Going over the Limit • run on "scorpio": • 4294967295 + 0 = 4294967295 • 4294967295 + 1 = 0 • 4294967295 + 2 = 1 • 4294967295 + 3 = 2 • 4294967295 + 4 = 3 • 4294967295 * 0 = 0 • 4294967295 * 1 = 4294967295 • 4294967295 * 2 = 4294967294 • 4294967295 * 3 = 4294967293 • 4294967295 * 4 = 4294967292 The variable restarts itself

19. Integers' Representation s means signnegative integers -in "2's complement" v means value

20. Integers' Representation (2) • signed char sc = -128; • unsigned char uc = 255; • sc = sc - 1; • uc = uc + 1; • uc = 255; • uc = uc*2; 1000 0000 1111 1111 0111 1111 = 127 Underflow 0000 0000 = 0 Overflow 1111 1111 1111 1110 = 254

21. Float representation • Decimal base: int.frac*10exp • 3/16 =0.1875 = 1.875*10-1 • 1000/3 = 333.33333... =3.333...*102 • Binary base: 1.frac*2exp • 3/16 = 3*2-4 = 1.5*2-3 = 1.1*2-11 • 1/10 = 1.1001100110011...*2-100 • Fixed size, limited accuracy. float = 4 bytes: • seee eeee efff ffff ffff ffff ffff ffff • double uses 8 bytes (64 = 1+11+52) • http://steve.hollasch.net/cgindex/coding/ieeefloat.html base 2 sign[1] exp+127[8] frac (mantissa)[23]

22. Float representation - limited accuracy • #include <stdio.h> • int main() • { • int i; • float f = 0; • for (i = 0; i < 100; ++i ) • f += 0.01; • printf( "%f\n", f ); • return 0; • } Output: 0.999999

23. Special float values • NaN – Not a Number. Represents an illegal value • printf("%f\n", sqrt(-1));will print-1.#IND00 or nan • INF – infinity • printf("%f\n", 1/0.0);will print1.#INF00 or inf

24. Mathematical Functions • sqrt(x) • pow(x,y) = xy • exp(x) =eX • log(x) • sin(x) • cos(x) • tan(x) All the functions use doubles(floats: sqrtf, powf,expf,...) The functions are declared in <math.h> Requires linking with math library:gcc -lm

25. #include <stdio.h> • #include <math.h> • int main(void) • { • double x = 0; • printf( "\nThe square root of x and x raised" • "\nto the x power will be computed.\n---\n\n" ); • while ( 1 ) • { • 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; • } Infinite Loop

26. The Result of the Program • The square root of x and x raised • to the x power will be computed. • --- • Input x: 2 • x = 2.000000000000000e+00 • sqrt(x) = 1.414213562373095e+00 • pow(x, x) = 4.000000000000000e+00 • Input x:

27. The usual arithmetic conversion (promotion) • If eitheroperand is of type long double, double, float or unsigned long, the other operand is converted to long double, double, float or unsigned long appropriately. • Otherwise, the "integral promotions" are performed on both operands, and the following rules are applied: • If one operand has type long and the other operand has type unsigned then one of two possibilities occurs: • If a long can represent all the values of an unsigned, then the operand of type unsigned is converted to long. • If a longcannot represent all the values of an unsigned, then both operands are converted to unsigned long. • Otherwise, if either operand is of type long, the other operand is converted to long. • Otherwise, if either operand is of type unsigned, the other operand is converted to unsigned. • Otherwise, both operands have type int.

28. Expressions and Types • char c; short s; int i; unsigned u; unsigned long ul;float f; double d; long double ld;

29. Cast • double d = 3.3; • int i = 0; • unsigned ui = 0; • char c; • i = (int)d; • d = (double)i / 2; • ui = (unsigned)i; • c = 882; i == trunc(d) = 3 d == 1.5 882 = 0x372  overflow  c == 0x72=114(behavior in case of overflow is undefined ANSI C)