C/C++/Java 的基本数据类型

变换类型

C

C++

Java

char c --> int i

i = c - ‘0’

i = c - ‘0’

i = c - ‘0’

int i --> char c

c = i + ‘0’

c = i + ‘0’

c = i + ‘0’

char *s(String s) --> int i

i = atoi(s)

i = stoi(s)

i = Integer.parseInt(s)

char *s(String s) --> float f

f = atof(s)

f = stof(s)

f = Float.parseFloat(s)

char *s(String s) --> double d

d = atof(s)

d = stod(s)

d = Double.parseDouble(s)

int i --> char *s(String s)

s = itoa(int i, char *str, int radix)

s = to_string(i)

s = String.valueOf(i)

float/double f --> char *s(String s)

sprintf(char *s, const char *format,…)

s = to_string(f)

s = String.valueOf(f)

基本类型

32位编译器/单位Byte

64位编译器/单位Byte

char

1

1

char*

4

8

short

2

2

int

4

4

unsigned int

4

4

long

4

8

long long

8

8

float

4

4

double

8

8

基本类型

单位Byte

取值范围

byte

1

0/1

boolean

1

true/false

char

2

0~65535(2¹⁶-1)

short

2

-32768(-2¹⁵)~32767(2¹⁵-1)

int

4

-2³¹~2³¹-1

long

8

-2⁶³ ~ 2⁶³-1

float

4

单精度浮点数字长32位，尾数长度23，指数长度8，指数偏移量127

double

8

双精度浮点数字长64位，尾数长度52，指数长度11，指数偏移量1023