[理学]C_Programming_Language_-Data_Types_Operators_and_Expressions.ppt

Data types, Operator Expression Outline Data, Data Types Size Constants and Variables Operators Expression Type Conversion Problem There is a circle swimming pool, we want to decorate it. So circumference needed. Data － the processed object of a program. sum = 1+2; printf(“%d”,sum); sum = n1 + n2; Data type － define data structure, data size, data operation Data Types in C Data Sizes Different data type has different storage Size Outline Data, Data Types Size Constants and Variables Operators Expression Type Conversion Constants Constants Some characters can not be represented by ‘ ‘, so escape sequence(转义字符) provided. Symbolic constant Symbolic constant #define ONE 1 #define COM “company” #define MAX 100 #define TWO ONE+ONE a= b+2; printf (“%s”, “company”); int array[100]; a= b+ TWO; printf(“%s”,COM); int array[MAX]; Variable name ? Identifier declaration form: data type variable name; A variable can be initialized in its declaration. Form: data type variable name =expression ; Integral Data size and range On 16-bit Platform Integral variable Examples Examples: A program to add two numbers： Floating point Data size and range Floating point Data example Example: display a b on the screen void main( ) { float a; double b; a=12345.6789; b=0.1234567891234567899e15; printf(a=%f,b=%f\n,a,b); } Outline Data, Data Types Size Constants andVariables Operators Expression Type Conversions Expression Operator Operator Precedence (P) Associativity (A) Question: in mathematical form , if x ‘s value is between 0 and 10, we can write it like (0≤x≤10), In C, How to code it? 0 =x =10 right? Or not? Examples: int x=7, y=10; high bits are o