The difference between int,signed int and unsigned int and printf%u,%d

############## #首先 ###############
Signed int signed integral type
unsigned int non-symbolic integer
int is signed int, which is written with [signed] int to indicate signed can omit

2^31=2147483648
2^31-1=2147483647
2^32=4294967296
2^32-1=4294967295

############## #对有符号整型 ###############
range from-2147483648 to -1=2^31 = 2,147,483,648
The binary is expressed as a complement, with the highest bit 1 beginning:
1000 0000 0000 0000 0000 0000 0000 0000->-2147483648
1000 0000 0000 0000 0000 0000 0000 0001->-2147483647
...
1111 1111 1111 1111 1111 1111 1111 1110->-2
1111 1111 1111 1111 1111 1111 1111 1111->-1

range from 0 to 2147483647 =2^31 = 2,147,483,648
The binary uses the complement (the positive source code inverse code complement) to indicate that the highest bit 0 begins:
0000 0000 0000 0000 0000 0000 0000 0000-> 0
0000 0000 0000 0000 0000 0000 0000 0001-> 1
...
0111 1111 1111 1111 1111 1111 1111 1110-> 2147483646
0111 1111 1111 1111 1111 1111 1111 1111-> 2147483647

############## #对无符号整型 ###############
Unsigned is the highest bit does not represent a sign bit, still used as a numeric bit
range from 0 to 4294967295=2^32 = 4,294,967,296

############## #关于printf的打印 ###############
%d signed
%u no sign

Signed int i =-3; That is i=11111111111111111111111111111101 (signed number 3)
unsigned int i2 = -13;//= i=11111111111111111111111111110011 (signed number-13)
(1)
printf ("I's value is%d\n", i);//Parse I to a signed integer, output: I has a value of-3
printf ("I2 value is%d\n", i2);//Parse I to a signed integer, output: The value of i2 is-13
(2)
printf ("I's value is%u\n", i);//Parse I to a signed integer, output: I has a value of 4294967293 (that is, =4294967295-2)
printf ("I2 value is%u\n", i2);//Parse I to signed integer, Output: I2 value is 4294967283 (that is, =4294967295-12)

for (1) is signed as-is parsing, the highest bit is the symbol bit
for (2) is unsigned parsing, the highest bit is treated as a numerical bit