博客
关于我
Variables and Types 变量和类型
阅读量:192 次
发布时间:2019-02-28

本文共 2533 字,大约阅读时间需要 8 分钟。

 


Data types   数据类型

C has several types of variables, but there are a few(一些) basic types:

  • Integers (整型)- whole numbers which can be either positive(正数) or negative(负数)(要么...要么). Defined using charintshortlong or long long.

  • Unsigned integers(无符号整型) - whole numbers which can only be positive. Defined  using unsigned char,  unsigned int,   unsigned shortunsigned long or unsigned long long.

  • Floating point numbers(浮点数) - real numbers实数 (numbers with fractions). Defined using float and double.

  • Structures(结构体) - will be explained later, in the Structures section.(稍后将在“结构”一节中解释。)
     

The different types of variables define their bounds(界限). A char can range(范围) only from -128 to 127, whereas a long can range from -2,147,483,648 to 2,147,483,647 (long and other numeric data types(数字数据类型) may have another range on different computers, for example - from –9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 on 64-bit computer).

Note that C does not have a boolean type(布尔类型). Usually, it is defined using the following notation(符号):

#define BOOL char#define FALSE 0#define TRUE 1

C uses arrays of characters(字符数组) to define strings(字符串), and will be explained in the Strings section.

Defining variables  定义变量

For numbers(数字), we will usually use the type int, which an integer in the size of a "word"(字)the default number size of the machine which your program is compiled on. On most computers today, it is a 32-bit number, which means the number can range from -2,147,483,648 to 2,147,483,647.

To define the variables foo and bar, we need to use the following syntax(语法):

int foo;int bar = 1;

The variable foo can be used, but since we did not initialize(初始化) it, we don't know what's in it. The variable bar contains(包含) the number 1.

Now, we can do some math. Assuming(假设) abcd, and e are variables, we can simply use plus, minus and multiplication(乘法) operators in the following notation, and assign(分配,赋值) a new value to a:

int a = 0, b = 1, c = 2, d = 3, e = 4;a = b - c + d * e;printf("%d", a); /* will print 1-2+3*4 = 11 */

Exercise

In the next exercise, you will need to create a program which prints out the sum of the numbers ab, and c.

原:

#include 
int main() { int a = 3; float b = 4.5; double c = 5.25; float sum; /* Your code goes here */ printf("The sum of a, b, and c is %f.", sum); return 0;}

 

改:

#include 
int main() { int a = 3; float b = 4.5; double c = 5.25; float sum; /* Your code goes here */ sum = a + b + c ; printf("The sum of a, b, and c is %f.", sum); return 0;}

 

 

转载地址:http://fnii.baihongyu.com/

你可能感兴趣的文章
mysql的函数DATE_ADD()
查看>>
mysql的函数操作
查看>>
mysql的分类排名_mysql高低排名
查看>>
Mysql的分表设计方法 (水平分表和垂直分表)
查看>>
mysql的分页查询limit关键字
查看>>
MySql的创建数据表、约束、外键约束的创建修改删除、级联操作
查看>>
MySQL的删除修改的实验目的_基础篇 - 数据库及表的修改和删除
查看>>
MySQL的四大隔离级别,你都知道哪些?
查看>>
MySQL的四种事务隔离级别
查看>>
MySQL的基本命令
查看>>
Mysql的备份与恢复类型
查看>>
mysql的大小写对性能的影响问题
查看>>
mysql的密码管理、mysql初始密码查找、密码修改、mysql登录
查看>>
mysql的常见八股文面试题
查看>>
MySQL的常见命令
查看>>
mysql的引擎以及优缺点_MySQL有哪些存储引擎,各自的优缺点,应用场景-阿里云开发者社区...
查看>>
MySQL的操作:
查看>>
mysql的数据类型有哪些?
查看>>
MYSQL的最左匹配原则的原理讲解
查看>>
mysql的语法规范
查看>>