C language operators:
Arithmetic Operators
Assignment Operators
Relational Operators
Logical Operators
Ternary operator
Arithmetic operators:
Divide operation Note: If the division of two numbers are integers , then the result is also an integer , fractional part omitted, such as 8/3 = 2; and the two numbers have a decimal , the result was decimals , such as: 9.0 / 2 = 4.500000.
Remainder calculation Note: this operation is only suitable for two integers performed modulo operation, such as: 3 = 10% 1; 3 and 10.0% is wrong; symbols depending on the sign of the arithmetic modulus, such as ( -10)% 3 = 1; in 10% (- 3) = 1.
Note: C language is not the exponentiation operator, nor can ×, ÷ arithmetic signs and the like.
Increment decrement operator: increment operator is "+", which is a function of the variable value is incremented by one; decrement operator is "-", whose function is to subtract 1 from the value of the variable. They are often used in a loop.
Note: Whether a ++ or ++ a are equivalent to a = a + 1, the value of a finished after expression are incremented by 1, regardless of a-- or --a are equivalent to a = a-1 , after the value of a finished expression are reduced from 1.
Note: increment operator (+) and decrement operator (-) can only be used for variable or constant and can not be used for expression. Like 5++or (a+b)++they are not legitimate. Because 5 is a constant, constant value can not be changed. (a+b)++It is impossible to achieve.
Assignment operator (including the simple assignment operator and the compound assignment operators):
Example: integer variable is defined and assigned to a. 3, a + = 5; this formula is equivalent to a = a + 5; then assigned to a variable a and 5 after the addition.
Note: space does not exist between the composite operators and operators in the equal sign.
Relational operators:
Relational expressions is "true" and "false", represented by integers 1 and 0 in the C program.
Note:> =, <=, ==, = space between such symbols can not exist!.
Logical Operators:
Value of the logic operation are also two "true" and "false", C language using integer 0 and 1 are represented.
Evaluation rules as follows:
1) and operation (&&): involved in computing two variables are true , the result was true , and false otherwise.
2) OR operation (||): two variables involved in the operation as long as one is true , the result will be true . Two quantities are false, the result is false.
3) non-operation ():! Variables involved in computing is true , the result is false ; involved in computing the amount of time is false , the result is true .
Ternary operator: C language ternary operator: "?:"
The format is: Expression 1 Expression 2:? Expression 3;
First determine whether the value of the expression 1 is true, if it is true, then executing the expression 2; if it is false, then the expression is executed 3.
Operators Competition compare the priority: Priority is the order of operations in the calculation.
Priority 1 is the highest priority, the priority level is the lowest priority 10.
Example: If the data type int and float or double data type operation, first type int and float type data into double-data, and then calculates, as a result of double type.
Cast:
Its role is the calculation result of the expression cast to type descriptions Type symbol represents.
Note the following issues when using cast:
1, data type and the expression must be in parentheses .
2、转换后不会改变原数据的类型及变量值，只在本次运算中临时性转换。
3、强制转换后的运算结果不遵循四舍五入原则。
printf 和 scanf 中的格式字符：
在输入函数时，用 %c 格式声明输入字符时，空格字符和转义字符都是作为有效字符输入。
在使用 %d 输出时，我们可以指定输出的宽度。
具体用法:
%d：按照整型数据的实际长度输出。
%md：以m指定的字段宽度输出，右对齐。
%ld：输出长整型数据。
%mld：输出指定宽度的长整型数据。
用 putchar 函数输出一个字符：一般形式：putchar(c); 功能：输出变量 c 所代表的一个字符； 说明：c 为字符型变量或整型变量。
用 getchar 函数输入一个字符：一般形式：getchar(); 功能：要求用户从终端（键盘）输入单个字符； 说明：返回值为从输入设备上得到的字符。