The storage, representation and basic arithmetic of-----data program in C + + basic knowledge learning

Just started to learn C + +, reading summed up a little note, one record down for easy follow-up review, and I hope I can be the same little white a little help

Storage, representation and basic operation of data programs

1.1/1.2 (chapter of the book)
{
1. Separate the contents of the input with a space

2. The Declaration of a function is similar to a name, and it is only necessary to write the function in the main function before the function call in the main function to declare

3.c++ output format:cout<< output content <<endl; input format:cin>> input content;

4. The main function is generally defined as type int: Yes returns 1, otherwise returns 0;

5. The name of the namespace cannot be duplicated;

6. Variables, functions in different names can have the same name, call format b::fun ()//define namespace B namespace B;

7.string Type: Initialization of String type: 1.string s1; S1 is an empty string S2 ("ABC"); Initializes s2string S3 (S2) with string values; Initialize the S3 to a copy of S2 string S4 (N, ' C '); Initialize the S4 to n ' C ';
Action: 1.s.empty () returns TRUE if S is null, otherwise returns FALSE, 2.s.size () returns the number of characters in the string, 3.s[n] returns the nth character in the string, starting with 0, 4.s1+s2 joins the S1,S2 and returns the new value; s1= S2 replaces the value of S1 with S2; V1==v2 determines that it returns true, otherwise it returns false;
s5= "Hello" + "world" is illegal;
}
1.3
{
1. Single-line comment is//comment content; Multiline comment */* Comment content */

2. A function includes 1. preprocessing commands, 2. Global declaration section, 3. function; cout1.txt

3. The end of the output statement must have Endl;

The data type bool (true; false) that is specifically used in 4.c++;

5. How to represent floating-point numbers:
(1). Decimal: Generally by default double-precision processing, after the data plus F is a single precision (four bytes), after the data is added l/l to double precision (eight bytes)
(2). Exponential form: E12 represents ten of the 12-time Square

6. Escape character: \a bell; \ n newline; \ t horizontal tabulation (jumps to the next tab position ...) \b Backspace; \ r Enter; \f, \v vertical tab; \ \ backslash \
\ ' single quote character; \ ' double-quote character; \ddd character; the characters represented by the octal number of the decimal place; The character represented by the hexadecimal number of \xhh;

7. The identifier must be a letter, underscore, number, and the first character must be a letter and an underscore;

8.c++ defines the variables used: defined first, then used, and must indicate the data type, the variable must be initialized;

9. Before the defined variable is const, the value of the variable cannot be changed during the program's operation (also known as a constant variable), but the constant variable must be assigned at the same time as the definition;

10. Operator:% is divisible by the remainder;! = is not equal to;& fetch address operator; sizeof number of bytes operator

11. In C + + operation, all float types are processed by double type;

12. Coercion type conversion: (double) A converts a to a double type, (int) (X+Y) Converts the value of the x+y to an integer type;
The form is: typically (type name) (expression) new type name (expression) in C + +

13. The comma operator: The general form: expression 1, Expression 2, the solution is to find the expression 1, then the expression 2, the entire comma expression value is the value of the expression 2; In most cases, the purpose of the comma expression is to get the value of each expression separately, instead of using or getting the final value of the comma-expression

The storage, representation and basic arithmetic of-----data program in C + + basic knowledge learning