The basic syntax.

1. The basic data types common space (64-bit machine, for example)

   •  char: 1 byte
   •  int: 4 bytes
   •  float: 4 bytes
   •  double: 8 bytes

   Basic types of writing

   <p an integer>

   •  a, default is 10 decimal, 10, 20.
   •  b, beginning with 0 as octal, 045,021.
   •  c., beginning with 0b as binary, 0b11101101.
   •  d, beginning with 0x hexadecimal, 0x21458adf.

   Decimal

   Single-precision constants: 2.3f.

   Double constant: 2.3, the default double precision.

   Character constants

   Enclosed in single quotation marks, save only the character 'a', 'b', '*', as well as the escape character '\ n', '\ t'.

   String constant

   English double quotation marks can be saved due to multiple characters: "abc".

   1, data type conversion: C if a language expression contains different types of constants and variables in the calculation, they will be automatically converted to the same type; may be cast data types in the C language;

   2, automatic conversion rules:

   (  A) floating-point number is assigned to an integer, the decimal floating-point numbers are discarded;

   (  B) float from integer, the same value, but is stored in the corresponding floating-point variables;

   3, cast in the form:  (type specifier) (expression)

2. Examples of program:

   #include<stdio.h>
   
   int main() {     float f,x=3.6,y=5.2;     int i=4,a,b;     a=x+y;     b=(int)(x+y);     f=10/i;     printf("a=%d,b=%d,f=%f,x=%f\n",a,b,f,x); }

   In the first embodiment was 8.8 x + y is calculated, and then assigned to a, since a is an integer, the integer part Pickup 8, a = 8;

   Next, the b x + y is an integer cast;

   Finally, 10 / i is an integer of two division, the result remains an integer of 2, the floating-point number is assigned to F 2;

   x is a floating-point output directly.