Java 没有无符号数

C语言的无符号数

C语言里的int一般分为unsigned int和singed int <=>int
下面是我写的一段测试代码：

#include <cstdio>using namespace std;int main(){    unsigned int u_a=0;    signed int s_a=0;    int n_a=0;    printf("u_a=%u\n",u_a);    printf("s_a=%u\n",s_a);    printf("n_a=%u\n",n_a);    printf("=======================================\n");    unsigned int u_b=4294967295;    signed int s_b=4294967295;    int n_b=-1;    printf("u_b=%u\n",u_b);    printf("s_b=%d\n",s_b);    printf("n_b=%d\n",n_b);    printf("=======================================\n");    unsigned int u_c=1;    signed int s_c=1;    int n_c=1;    printf("u_c=%u\n",u_c);    printf("s_c=%u\n",s_c);    printf("n_c=%u\n",n_c);    printf("=======================================\n");    printf("size of this three kinds of ints\n");    printf("size of unsigned int=%d\n",sizeof(unsigned int));    printf("size of signed int =%d\n",sizeof(signed int));    printf("size of int =%d\n",sizeof( int));    return 0;}

输出结果为：

在我的电脑里int是4个字节，最大值是4294967295
于是unsigned int的范围是0~4294967295

Java中的int

java只有八种基本数据类型：byte,short,char,bool,int ,long,double,float
而且java中各个基本数据类型的大小是固定的。
java中的int是4个字节32位。
范围是：-2147483648”到“2147483647

测试代码

public class PrintInt {    public static void main(String[] args) {      System.out.println("max int ="+Integer.MAX_VALUE);      System.out.println("min int ="+Integer.MIN_VALUE);    }}

运行结果

max int =2147483647min int =-2147483648