C Language learning

1. Define constants

usage ： #define Constant names value

const data type Constant names = value

2. integer int

Print format

Print format	meaning
%d	Output one A signed Decimal system of int type
%o（ Letter o）	Output 8 It's binary int type
%x	Output 16 It's binary int type , Letters are output in lowercase
%X	Output 16 It's binary int type , Output letters in uppercase
%u	Output one 10 It's binary An unsigned number

Example

#include <stdio.h>
int main(void)
{
    
    // data type   identifier  = value 
    // Unsigned  unsigned  A signed  signed
    signed a =-10;
    //unsigned int a =10  This can be displayed normally   If =-10 when   There will be garbled code 
    printf("%d\n",a);// here  unsigned  It can output normally -10
    //printf("%u\n",a);
    return 0;
}

#include <stdio.h>
int main(void)
{
    
    int a=10;
    printf("%d\n",a);// Output 10
        printf("%x\n",a);// Output a
        printf("%X\n",a);// Output A
        printf("%o\n",a);// Output 12
    // Define octal data to 0 start 
    int b =0123;
     // Definition 16 Hexadecimal data   With 0x start 
        int c =0x123;
     printf("%x\n",b);
     printf("%X\n",b);
     printf("%o\n",b);
     printf("%x\n",c);
     printf("%X\n",c);
     printf("%o\n",c);
        return 0;
    
   
}