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替换表的字段里面内容
查看>>
MySQL最多能有多少连接
查看>>
MySQL最大建议行数 2000w,靠谱吗?
查看>>
MySQL有哪些锁
查看>>
MySQL服务器安装(Linux)
查看>>
mysql服务器查询慢原因分析方法
查看>>
mysql服务无法启动的问题
查看>>
MySQL杂谈
查看>>
mysql权限
查看>>
mysql条件查询
查看>>
MySQL条件查询
查看>>
MySQL架构与SQL的执行流程_1
查看>>
MySQL架构与SQL的执行流程_2
查看>>
MySQL架构介绍
查看>>
MySQL架构优化
查看>>
mysql架构简介、及linux版的安装
查看>>
MySQL查看数据库相关信息
查看>>
MySQL查看表结构和表中数据
查看>>
MySQL查询优化:LIMIT 1避免全表扫描
查看>>
MySQL查询优化之索引
查看>>