erand48(X） 在 C++ 中不起作用，Visual Studio 12

erand48(X) not working in C++ , Visual Studio 12

本文关键字：不起作用 Visual Studio C++ erand48      更新时间：2023-10-16

我有C++代码，其中有几行erand48(X)，Visual Studio在这方面给出了Unable to identify错误。我在网上搜索，发现erand48()在Visual Studio（或Windows）中不存在。建议是自己编写实现。任何人都可以为我提供这方面的实现，因为我是新手，而且我的时间很短，无法为此花费太多时间。

此外，很少有一行以uniform开头，如uniform sampler2D Texture，它给出的错误the value or constructor 'uniform' not defined。为什么显示此错误以及如何删除此错误？

改用uniform_real_distribution类。

#include <random>
#include <iostream>
std:: default_random_engine generator;
std::uniform_real_distribution<double> distr(0.0,1.0);
double erand48(int X){
    return distr(generator);
}
int main(){
    std::cout << erand48(1) << std::endl;
    return 0;
}

或者只是使用LibGW32C for windows

我也在寻找这种erand48方法（使用 Visual Studio 2015），因为

  1. 它是线程安全的，
  2. 调用方必须保持并通过状态，
  3. 它是纯C（不要问我哪个版本，它对我来说已经足够旧了）。

因此，我将通过提供可能的实现本身来回答问题，而不是提供（C++）替代方案。

#pragma once
#include <stdlib.h>
#include <math.h>
#define RAND48_SEED_0   (0x330e)
#define RAND48_SEED_1   (0xabcd)
#define RAND48_SEED_2   (0x1234)
#define RAND48_MULT_0   (0xe66d)
#define RAND48_MULT_1   (0xdeec)
#define RAND48_MULT_2   (0x0005)
#define RAND48_ADD      (0x000b)
unsigned short _rand48_seed[3] = {
    RAND48_SEED_0,
    RAND48_SEED_1,
    RAND48_SEED_2
};
unsigned short _rand48_mult[3] = {
    RAND48_MULT_0,
    RAND48_MULT_1,
    RAND48_MULT_2
};
unsigned short _rand48_add = RAND48_ADD;
void _dorand48(unsigned short xseed[3]) 
{
    unsigned long accu;
    unsigned short temp[2];
    accu = (unsigned long)_rand48_mult[0] * (unsigned long)xseed[0] +
        (unsigned long)_rand48_add;
    temp[0] = (unsigned short)accu;        /* lower 16 bits */
    accu >>= sizeof(unsigned short) * 8;
    accu += (unsigned long)_rand48_mult[0] * (unsigned long)xseed[1] +
        (unsigned long)_rand48_mult[1] * (unsigned long)xseed[0];
    temp[1] = (unsigned short)accu;        /* middle 16 bits */
    accu >>= sizeof(unsigned short) * 8;
    accu += _rand48_mult[0] * xseed[2] + _rand48_mult[1] * xseed[1] + _rand48_mult[2] * xseed[0];
    xseed[0] = temp[0];
    xseed[1] = temp[1];
    xseed[2] = (unsigned short)accu;
}
double erand48(unsigned short xseed[3])
{
    _dorand48(xseed);
    return ldexp((double)xseed[0], -48) +
        ldexp((double)xseed[1], -32) +
        ldexp((double)xseed[2], -16);
}
double drand48(void)
{
    return erand48(_rand48_seed);
}
long lrand48(void) 
{
    _dorand48(_rand48_seed);
    return ((long)_rand48_seed[2] << 15) + ((long)_rand48_seed[1] >> 1);
}
long nrand48(unsigned short xseed[3]) 
{
    _dorand48(xseed);
    return ((long)xseed[2] << 15) + ((long)xseed[1] >> 1);
}
long mrand48(void) 
{
    _dorand48(_rand48_seed);
    return ((long)_rand48_seed[2] << 16) + (long)_rand48_seed[1];
}
long jrand48(unsigned short xseed[3]) 
{
    _dorand48(xseed);
    return ((long)xseed[2] << 16) + (long)xseed[1];
}
void srand48(long seed) 
{
    _rand48_seed[0] = RAND48_SEED_0;
    _rand48_seed[1] = (unsigned short)seed;
    _rand48_seed[2] = (unsigned short)(seed >> 16);
    _rand48_mult[0] = RAND48_MULT_0;
    _rand48_mult[1] = RAND48_MULT_1;
    _rand48_mult[2] = RAND48_MULT_2;
    _rand48_add = RAND48_ADD;
}
unsigned short *seed48(unsigned short xseed[3]) 
{
    static unsigned short sseed[3];
    sseed[0] = _rand48_seed[0];
    sseed[1] = _rand48_seed[1];
    sseed[2] = _rand48_seed[2];
    _rand48_seed[0] = xseed[0];
    _rand48_seed[1] = xseed[1];
    _rand48_seed[2] = xseed[2];
    _rand48_mult[0] = RAND48_MULT_0;
    _rand48_mult[1] = RAND48_MULT_1;
    _rand48_mult[2] = RAND48_MULT_2;
    _rand48_add = RAND48_ADD;
    return sseed;
}
void lcong48(unsigned short p[7]) 
{
    _rand48_seed[0] = p[0];
    _rand48_seed[1] = p[1];
    _rand48_seed[2] = p[2];
    _rand48_mult[0] = p[3];
    _rand48_mult[1] = p[4];
    _rand48_mult[2] = p[5];
    _rand48_add = p[6];
}

"uniform sampler2D Texture"听起来像GLSL代码，这是OpenGL着色器代码，而不是C++。如果您的文件实际上是C++的，我想包含"uniform sampler2D"的行应该是着色器源字符串的一部分。

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