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C++ 中的数据类型范围及其宏

在竞争性编程中，通常需要将变量赋值为数据类型所能容纳的最大值或最小值。然而，记住这些大而精确的数字是一项困难的任务。因此，C++ 提供了一些宏来表示这些数字，这样可以直接将它们赋值给变量，而不必实际输入整个数字。以下是一些宏的列表：

数据类型

范围

宏的最小值

宏的最大值

char

-128 to +127

CHAR_MIN

CHAR_MAX

short char

-128 to +127

SCHAR_MIN

SCHAR_MAX

unsigned char

0 to 255

—

UCHAR_MAX

short int

-32768 to +32767

SHRT_MIN

SHRT_MAX

unsigned short int

0 to 65535

—

USHRT_MAX

int

-2147483648 to +2147483647

INT_MIN

INT_MAX

unsigned int

0 to 4294967295

—

UINT_MAX

long int

-9223372036854775808 to +9223372036854775807

LONG_MIN

LONG_MAX

unsigned long int

0 to 18446744073709551615

—

ULONG_MAX

long long int

-9223372036854775808 to +9223372036854775807

LLONG_MIN

LLONG_MAX

unsigned long long int

0 to 18446744073709551615

—

ULLONG_MAX

float

1.17549e-38 to 3.40282e+38

FLT_MIN

FLT_MAX

float (negative)

-1.17549e-38 to -3.40282e+38

-FLT_MIN

-FLT_MAX

double

2.22507e-308 to 1.79769e+308

DBL_MIN

DBL_MAX

double (negative)

-2.22507e-308 to -1.79769e+308

-DBL_MIN

-DBL_MAX

样例

以下示例展示了数据类型的宏。

Text Only
// 演示数据类型宏的 C++ 代码
#include <float.h> // 对于浮点数，双精度浮点数的宏
#include <iostream>
#include <limits.h> // 对于整型，字符型宏

using namespace std;

int main()
{
    //使用宏显示数据类型范围
    cout << "char ranges from: " << CHAR_MIN << " to "
         << CHAR_MAX << endl;
    cout << "\nshort char ranges from: " << SCHAR_MIN
         << " to " << SCHAR_MAX << endl;
    cout << "\nunsigned char ranges from: " << 0 << " to "
         << UCHAR_MAX << endl;

    cout << "\n\nshort int ranges from: " << SHRT_MIN
         << " to " << SHRT_MAX << endl;
    cout << "\nunsigned short int ranges from: " << 0
         << " to " << USHRT_MAX << endl;
    cout << "\nint ranges from: " << INT_MIN << " to "
         << INT_MAX << endl;
    cout << "\nunsigned int ranges from: " << 0 << " to "
         << UINT_MAX << endl;
    cout << "\nlong int ranges from: " << LONG_MIN << " to "
         << LONG_MAX << endl;
    cout << "\nunsigned long int ranges from: " << 0
         << " to " << ULONG_MAX << endl;
    cout << "\nlong long int ranges from: " << LLONG_MIN
         << " to " << LLONG_MAX << endl;
    cout << "\nunsigned long long int ranges from: " << 0
         << " to " << ULLONG_MAX << endl;

    cout << "\n\nfloat ranges from: " << FLT_MIN << " to "
         << FLT_MAX << endl;
    cout << "\nnegative float ranges from: " << -FLT_MIN
         << " to " << -FLT_MAX << endl;
    cout << "\ndouble ranges from: " << DBL_MIN << " to "
         << DBL_MAX << endl;
    cout << "\nnegative double ranges from: " << -DBL_MIN
         << " to " << -DBL_MAX << endl;

    return 0;
}

输出

Text Only
char ranges from: -128 to 127

short char ranges from: -128 to 127

unsigned char ranges from: 0 to 255

short int ranges from: -32768 to 32767

unsigned short int ranges from: 0 to 65535

int ranges from: -2147483648 to 2147483647

unsigned int ranges from: 0 to 4294967295

long int ranges from: -9223372036854775808 to 9223372036854775807

unsigned long int ranges from: 0 to 18446744073709551615

long long int ranges from: -9223372036854775808 to 9223372036854775807

unsigned long long int ranges from: 0 to 18446744073709551615

float ranges from: 1.17549e-38 to 3.40282e+38

negative float ranges from: -1.17549e-38 to -3.40282e+38

double ranges from: 2.22507e-308 to 1.79769e+308

negative double ranges from: -2.22507e-308 to -1.79769e+308

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