Question

我从C ++ Primary Plus编写了关于变量大小的程序这是代码：

#include <iostream>
#include <climits>
using namespace std;

int main() {
    int n_int = INT_MAX;
    short n_short = SHRT_MAX;
    long n_long = LONG_MAX;
    long long n_llong = LLONG_MAX;

    // wielkosc
    cout << "int is " << sizeof (int) << " bytes." << endl;
    cout << "short is " << sizeof n_short << " bytes."<< endl;
    cout << "long is " << sizeof n_long << " bytes." << endl;
    cout << "long long is " << sizeof n_llong << " bytes." << endl;
    cout << endl;

    cout << "Maximum values: "<< endl;
    cout << "int: " << n_int << endl;
    cout << "short: " << n_short << endl;
    cout << "long: " << n_long << endl;
    cout << "long long: " << n_llong<< endl << endl;
    cout << "Minimum int value = " << INT_MIN << endl;
    cout << "Bits per byte = " << CHAR_BIT << endl;
    return 0;
}

当我在Eclipse IDE中由Cygwin编译并运行时告诉我LONG_MAX = 9223372036854775807，这不是真的，我做错了什么？感谢。

实际输出：

int is 4 bytes.
short is 2 bytes.
long is 8 bytes.
long long is 8 bytes.

Maximum values: 
int: 2147483647
short: 32767
long: 9223372036854775807
long long: 9223372036854775807

Minimum int value = -2147483648
Bits per byte = 8

预期输出：

int is 4 bytes.
short is 2 bytes.
long is 8 bytes.
long long is 8 bytes.

Maximum values: 
int: 2147483647
short: 32767
long: 2 147 483 647
long long: 9223372036854775807

Minimum int value = -2147483648
Bits per byte = 8

Answer 1

你为什么这么肯定LONG_MAX！= 9223372036854775807？这对我来说似乎很好，因为2 ^ 63 -1 == 9223372036854775807.这意味着你的实现中long是64位，第一位用作符号位。请记住，标准并没有详细说明所有不同数据类型应该有多大 - 在Visual Studio的编译器上，long与int的大小相同，这有点烦人;）

LONG_MAX Cygwin的大小

1 个答案: