unsigned int l = ULONG_MAX; ○ 2 char c = -1; ○ 3 if (c == l) { ○ 4 printf("-1 = 4,294,967,295
Lecture
(This is a problem you will actually encounter later in this semester ) We can cast this character value to an integer value buy writing (int)e unsigned char c = 0xF0;
types
Unsigned Integer Data Types unsigned types: unsigned char, unsigned short, unsigned int, and unsigned long • Holds only non-negative integers • Conversion
DataTypes
Integer Constant Formats - normally signed ints unless a trailing L or U indicates long int and/or unsigned respectively Decimal [+-]1-9[0-9 ][LlUu] Optional
DataTypesSummary
Unsigned Integer Boundaries: Unsigned integers are defined in the c specification as being subject to modular arithmetic For an unsigned integer with width of X bits Arithmetic on that unsigned integer is done modulo 2x Arithmetic operations on a 16-bit unsigned integer is performed modulo 216
understanding c integer boundaries (overflows & underflow)
Signed and Unsigned Types in Interfaces Suppose unsigned type size_t for specifying how many bytes of mem- Programming Language C++,” April 1995
sep
At which points can overflow occur for signed and unsigned int? (assume binary values shown are all 32 bits) A Signed and unsigned can both
lect
Les types entiers bool : false ou true −→ booléen (seulement en C++) unsigned char : 0 à 255 (2 8 − 1) −→ entier très court (1 octet ou 8 bits) [signed] char
cours c annexe variables
conversion between signed and unsigned preserves bit patterns: char c = -1; unsigned char uc = c; int i = uc; printf(" d\n", i); // prints 255 float is 4 bytes and
c language