Chapter3 - Chapter 3 C BASICS C Variable Declaration...

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Unformatted text preview: Chapter 3 C++ BASICS C++ Variable Declaration Statements You must declare your variables: Syntax: type identifier; Integer types short i; // same as: signed short int i; 2-byte signed integer, -32,768 to 32,767 unsigned short int i; 2-byte unsigned integer, 0 to 65,535 long i; // same as: signed long int i; 4-byte signed integer, +-2,147,483,647 unsigned long int i; 4-byte unsigned integer, 0 to 4,294,967,295 Floating point types float x; 4-byte real, -10 38 to -10-38 or 0.0 or 10-38 to 10 38 7 significant digits double x; 8-byte real, +-308 exponent range 15 sig. digits Other types char c; Holds a single character, given in single quotes Example: char c = ‘A’; bool ok; Holds a true / false (0/1) value Example: bool ok = true; bool ok = x || y && (c > d); Examples int minutes; // 4-byte signed int short pounds; // 2-byte signed int long myBalance; // 4-byte signed int float acceleration; // 4-byte floating point double length; // 8-byte floating point Notes: cont. More than one variable can be declared in one declaration statement Example: int i,j,k = 2 ; Variable Value i ???????? j ???????? k 2 Notes: cont. A variable can be declared and initialized simultaneously. The right side can be an expression. Examples: int hours = 10; double pressure = 3.275 ; int minutes = hours* 60 ; Variable Value hours 10 pressure 3.275 minutes 600 Constant declaration It is customary to type the constant variable names in upper case The value of the constants ( IN_PER_FEET and PI in the examples above) may not be changed later in the program. PI = 3.14159 ; PI = 5.0 ; const int IN_PER_FEET = 12 ; const double PI = 22 / 7.0 ; ERROR!!!! C++ Constants Integer constants 163 0243 // octal, base 8, leading 0 0xa3 or 0XA3 // hexadecimal, base 16 Floating point constants 100. or 100.0 100.25 0.2 or .2 1.0025E12 or 1.0025e12 0.125E-7 float x = 100. ; float y = 100.0 ; int z = 100 ; C++ Constants Logical constants true/false // 0 or 0.0 means false, else true String constants “STRING” “ANOTHER !@#$%^& STRING” “He said, \”I\'m OK!\"\n" “123" ”A" C++ Constants Character constants 'A' '\n' //new line; '\r' //carriage return '\x31' //hex char code '\0' //null character ‘\a' //bell; '\t' //tab '\\' //backslash ' \' ' //single quote ' \" ' //double quote C++ Expressions and Assignment Statements Expressions, when evaluated, return a value. Expressions can be used in many places: assignment statements, if stmts., cout stmts., etc 1 + i i + j 7- 2 7 / 2 // integer division truncates 7 % 2 // modulo division, remainder 20 + 4 / 2 ( 20 + 4 ) / 2 sin( 1.5 )+j / k C++ Expressions and Assignment Statements Assignment Statements: variable = expression; i = 1; i = i + j; // or i += j; x = sqrt(cos(fabs(y)-z)); x = 3 / 4 ; // Integer division truncates!...
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This note was uploaded on 09/05/2011 for the course CGS 2421 taught by Professor Onal during the Fall '09 term at University of Florida.

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Chapter3 - Chapter 3 C BASICS C Variable Declaration...

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