编程导航

基础知识

  变量的类型有：

  1. 整数类型：int
  2. 浮点类型（小数类型）：double、float
  3. 字符类型：char
  4. 布尔类型：bool
  5. 字符串类型：string
  6. 数组类型：arry
  7. 对象类型：object

C++

查询变量信息

  查询值：

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#include <iostream>
using namespace std;

#define TestNumber 0

int main()
{
    int IntC = TestNumber;
    cout << "十六进制值：" << std::hex << IntC << endl;
    cout << "表达值：" << std::dec << IntC << endl;
}

点击测试代码

  查询地址，采用指针的方法：

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#include <iostream>
using namespace std;

#define TestNumber 0

int main()
{
    int IntC = TestNumber;
    cout << "地址：" << &IntC << endl;
}

点击测试代码

这种变量会在每次运行程序时随机分配，所以地址会发生变化。

  查询所占内存大小，使用函数 sizeof：

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#include <iostream>
using namespace std;

#define TestNumber 0

int main()
{
    int IntC = TestNumber;
    cout << "长度：" << sizeof(IntC) << endl;
}

点击测试代码

整型

无符号

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unsigned int UnsignedIntC = 0;
unsigned short int UnsignedShortIntC = 0;
unsigned short UnsignedShortC = 0;
unsigned long int UnsignedLongIntC = 0;
unsigned long UnsignedLongC = 0;
unsigned long long int UnsignedLongLongIntC = 0;
unsigned long long UnsignedLongLongC = 0;

未说明符号

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int IntC = 0;
short int ShortIntC = 0;
short ShortC = 0;
long int LongIntC = 0;
long LongC = 0;
long long int LongLongIntC = 0;
long long LongLongC = 0;

有符号

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signed int SignedIntC = 0;
signed short int SignedShortIntC = 0;
signed short SignedShortC = 0;
signed long int SignedLongIntC = 0;
signed long SignedLongC = 0;
signed long long int SignedLongLongIntC = 0;
signed long long SignedLongLongC = 0;

测试代码

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#include <iostream>
using namespace std;

#define TestNumber -1

int main()
{
    //整型
    //无符号
    unsigned int UnsignedIntC = TestNumber;
    unsigned short int UnsignedShortIntC = TestNumber;
    unsigned short UnsignedShortC = TestNumber;
    unsigned long int UnsignedLongIntC = TestNumber;
    unsigned long UnsignedLongC = TestNumber;
    unsigned long long int UnsignedLongLongIntC = TestNumber;
    unsigned long long UnsignedLongLongC = TestNumber;

    //无特殊说明
    int IntC = TestNumber;
    short int ShortIntC = TestNumber;
    short ShortC = TestNumber;
    long int LongIntC = TestNumber;
    long LongC = TestNumber;
    long long int LongLongIntC = TestNumber;
    long long LongLongC = TestNumber;

    //有符号
    signed int SignedIntC = TestNumber;
    signed short int SignedShortIntC = TestNumber;
    signed short SignedShortC = TestNumber;
    signed long int SignedLongIntC = TestNumber;
    signed long SignedLongC = TestNumber;
    signed long long int SignedLongLongIntC = TestNumber;
    signed long long SignedLongLongC = TestNumber;

    //变量
    cout << "变量" << endl;
    cout << "|" << "" << endl;
    //整型
    cout << "|_" << "整型，取值为：" << TestNumber << endl;
    cout << "| |" << "" << endl;
    //无符号
    cout << "| |_" << "无符号" << endl;
    cout << "| | |" << "" << endl;
    //整型 unsigned int
    cout << "| | |_" << "无符号整型 unsigned int" << endl;
    cout << "| | | |_" << "地址：" << &UnsignedIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(UnsignedIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << UnsignedIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << UnsignedIntC << endl;
    cout << "| | |" << "" << endl;
    //短整型 unsigned short int
    cout << "| | |_" << "无符号短整型 unsigned short int" << endl;
    cout << "| | | |_" << "地址：" << &UnsignedShortIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(UnsignedShortIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << UnsignedShortIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << UnsignedShortIntC << endl;
    cout << "| | |" << "" << endl;
    //短型 unsigned short
    cout << "| | |_" << "无符号短型 unsigned short" << endl;
    cout << "| | | |_" << "地址：" << &UnsignedShortC << endl;
    cout << "| | | |_" << "长度：" << sizeof(UnsignedShortC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << UnsignedShortC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << UnsignedShortC << endl;
    cout << "| | |" << "" << endl;
    //长整型 unsigned long int
    cout << "| | |_" << "无符号长整型 unsigned long int" << endl;
    cout << "| | | |_" << "地址：" << &UnsignedLongIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(UnsignedLongIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << UnsignedLongIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << UnsignedLongIntC << endl;
    cout << "| | |" << "" << endl;
    //长型 unsigned long
    cout << "| | |_" << "无符号长型 unsigned long" << endl;
    cout << "| | | |_" << "地址：" << &UnsignedLongC << endl;
    cout << "| | | |_" << "长度：" << sizeof(UnsignedLongC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << UnsignedLongC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << UnsignedLongC << endl;
    cout << "| | |" << "" << endl;
    //长长整型 unsigned long long int
    cout << "| | |_" << "无符号长长整型 unsigned long long int" << endl;
    cout << "| | | |_" << "地址：" << &UnsignedLongLongIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(UnsignedLongLongIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << UnsignedLongLongIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << UnsignedLongLongIntC << endl;
    cout << "| | |" << "" << endl;
    //长长型 unsigned long long
    cout << "| | |_" << "无符号长长型 unsigned long long" << endl;
    cout << "| | | |_" << "地址：" << &UnsignedLongLongC << endl;
    cout << "| | | |_" << "长度：" << sizeof(UnsignedLongLongC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << UnsignedLongLongC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << UnsignedLongLongC << endl;
    cout << "| |" << "" << endl;

    //无特殊说明
    cout << "| |_" << "无特殊说明" << endl;
    cout << "| | |" << "" << endl;
    //整型 int
    cout << "| | |_" << "整型 int" << endl;
    cout << "| | | |_" << "地址：" << &IntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(IntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << IntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << IntC << endl;
    cout << "| | |" << "" << endl;
    //短整型 short int
    cout << "| | |_" << "短整型 short int" << endl;
    cout << "| | | |_" << "地址：" << &ShortIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(ShortIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << ShortIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << ShortIntC << endl;
    cout << "| | |" << "" << endl;
    //短型 short
    cout << "| | |_" << "短型 short" << endl;
    cout << "| | | |_" << "地址：" << &ShortC << endl;
    cout << "| | | |_" << "长度：" << sizeof(ShortC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << ShortC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << ShortC << endl;
    cout << "| | |" << "" << endl;
    //长整型 long int
    cout << "| | |_" << "长整型 long int" << endl;
    cout << "| | | |_" << "地址：" << &LongIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(LongIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << LongIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << LongIntC << endl;
    cout << "| | |" << "" << endl;
    //长型 long
    cout << "| | |_" << "长型 long" << endl;
    cout << "| | | |_" << "地址：" << &LongC << endl;
    cout << "| | | |_" << "长度：" << sizeof(LongC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << LongC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << LongC << endl;
    cout << "| | |" << "" << endl;
    //长长整型 long long int
    cout << "| | |_" << "长长整型 long long int" << endl;
    cout << "| | | |_" << "地址：" << &LongLongIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(LongLongIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << LongLongIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << LongLongIntC << endl;
    cout << "| | |" << "" << endl;
    //长长型 long long
    cout << "| | |_" << "长长型 long long" << endl;
    cout << "| | | |_" << "地址：" << &LongLongC << endl;
    cout << "| | | |_" << "长度：" << sizeof(LongLongC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << LongLongC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << LongLongC << endl;
    cout << "| |" << "" << endl;

    //有符号
    cout << "| |_" << "有符号" << endl;
    cout << "| | |" << "" << endl;
    //整型 signed int
    cout << "| | |_" << "有符号整型 signed int" << endl;
    cout << "| | | |_" << "地址：" << &SignedIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(SignedIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << SignedIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << SignedIntC << endl;
    cout << "| | |" << "" << endl;
    //短整型 signed short int
    cout << "| | |_" << "有符号短整型 signed short int" << endl;
    cout << "| | | |_" << "地址：" << &SignedShortIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(SignedShortIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << SignedShortIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << SignedShortIntC << endl;
    cout << "| | |" << "" << endl;
    //短型 signed short
    cout << "| | |_" << "有符号短型 signed short" << endl;
    cout << "| | | |_" << "地址：" << &SignedShortC << endl;
    cout << "| | | |_" << "长度：" << sizeof(SignedShortC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << SignedShortC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << SignedShortC << endl;
    cout << "| | |" << "" << endl;
    //长整型 signed long int
    cout << "| | |_" << "有符号长整型 signed long int" << endl;
    cout << "| | | |_" << "地址：" << &SignedLongIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(SignedLongIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << SignedLongIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << SignedLongIntC << endl;
    cout << "| | |" << "" << endl;
    //长型 signed long
    cout << "| | |_" << "有符号长型 signed long" << endl;
    cout << "| | | |_" << "地址：" << &SignedLongC << endl;
    cout << "| | | |_" << "长度：" << sizeof(SignedLongC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << SignedLongC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << SignedLongC << endl;
    cout << "| | |" << "" << endl;
    //长长整型 signed long long int
    cout << "| | |_" << "有符号长长整型 signed long long int" << endl;
    cout << "| | | |_" << "地址：" << &SignedLongLongIntC << endl;
    cout << "| | | |_" << "长度：" << sizeof(SignedLongLongIntC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << SignedLongLongIntC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << SignedLongLongIntC << endl;
    cout << "| | |" << "" << endl;
    //长长型 signed long long
    cout << "| | |_" << "有符号长长型 signed long long" << endl;
    cout << "| | | |_" << "地址：" << &SignedLongLongC << endl;
    cout << "| | | |_" << "长度：" << sizeof(SignedLongLongC) << endl;
    cout << "| | | |_" << "十六进制值：" << std::hex << SignedLongLongC << endl;
    cout << "| | | |_" << "表达值：" << std::dec << SignedLongLongC << endl;
}

点击测试代码

总结

  1. 无论有符号或者无符号，都可以初始化位一个十进制的负数，都会用相同的补码存储下来，只是表达值不同而已。
  2. 无特殊说明的都是有符号的整型。
  3. 短型不会超过普通的整型，长型不会短于普通的整型。但是具体长度会因为系统位数发生改变。

规范

  其中，Signed 可以省略，默认就是有符号的。而对于长短整型，int 就可以省略。但是后面就不进行省略（缩写）了，写全拼。因为虽然简化了，但是可读性变差了。总结下来就是以下内容：

无符号

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unsigned int UnsignedIntC = 0;
unsigned short int UnsignedShortIntC = 0;
unsigned long int UnsignedLongIntC = 0;
unsigned long long int UnsignedLongLongIntC = 0;

有符号

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signed int SignedIntC = 0;
signed short int SignedShortIntC = 0;
signed long int SignedLongIntC = 0;
signed long long int SignedLongLongIntC = 0;

四个无符号的，四个有符号的。核心是四个：整型、短整型、长整型、长长整型。