procedure eraseSubstr(const pos:vector; var text:string; const pattern:string);
var
len, iter, end_, endPos:Integer;
t:string;
begin
t:=text;
len:=Length(pattern);
if (Length(pos) < 2) then
begin
Delete(t, pos[0], length);
end;
end;
错误发生在函数上Delete。
错误 -[dcc32 Error] Functions.pas(58): E2029 '(' expected but ')' found
有没有人经历过这个？请帮忙。
我绘制了两个不同比例的图表，但我无法将它们沿 w 轴组合。需要根据 0 = -pi 的原理将 L(w) 和 -Fi(w) 结合起来。我在 python + matplotlib 中绘图。
import matplotlib.pyplot as plt
import numpy as np
def W(w):
return 36.69487 / (0.00008214*(1j*w)**4 + 0.017538*(1j*w)**3 + 26.440677*(1j*w)**2 + (1j*w))
def A(w):
resW = W(w)
return np.sqrt(resW.real**2 + resW.imag**2)
def L(w):
return 20*np.log10(A(w))
def Fi(w):
resW = W(w)
U, V = resW.real, resW.imag
return np.arctan(V/U)
w = np.linspace(0.01, 1000, 1000)
wzero = np.zeros(w.shape)
fig, ax = plt.subplots()
ax1 = ax.twinx()
ax.plot(w, L(w),color='r')
ax1.plot(w,-Fi(w)-np.pi,color='b')
plt.xscale('log')
plt.xlim([0.01,100])
ax.set_ylabel('L(w)')
ax1.set_ylabel('-Fi(w)')
我从汇编模块导入一个函数，在调试中一切正常，但在发布中一切都停止工作。我不明白为什么。主程序用C++（Visual Studio 2019）编写，汇编模块由MASM编译。
主程序(C++)
#include <iostream>
void print(short** arr, const short m, const short n);
void print_vec(short* v, const int n);
extern "C" void __cdecl mat_vec_mul(short** mat, short* vec, short* vec_res, const short m, const short n);
int main()
{
const short M = 3;
const short N = 2;
short** matrix = new short* [M];
short* vec = new short [N];
for (short i = 0; i < N; i++)
{
vec[i] = i + 1;
}
short* vec_res = new short [M];
for (short i = 0, el = 1; i < M; i++)
{
matrix[i] = new short[N];
for (short j = 0; j < N; j++, el++)
{
matrix[i][j] = el;
}
}
std::cout << "Source matrix" << std::endl;
print(matrix, M, N);
std::cout << "\nSource vector" << std::endl;
print_vec(vec, N);
//prototype of mul in c++
//for (short i = 0; i < M; i++)
//{
// vec_res[i] = 0;
// for (short j = 0; j < N; j++)
// {
// vec_res[i] += matrix[i][j] * vec[j];
// }
//}
mat_vec_mul(matrix, vec, vec_res, M, N);
std::cout << "\n\nResult vector" << std::endl;
print_vec(vec_res, M);
delete[]vec;
delete[]vec_res;
for (short i = 0; i < M; i++)
{
delete[]matrix[i];
}
delete[]matrix;
std::cin.get();
std::cin.get();
return 0;
}
void print(short** arr, const short m, const short n)
{
for (short i = 0; i < m; i++)
{
for (short j = 0; j < n; j++)
{
std::cout << arr[i][j];
if (j != n - 1)
std::cout << " ";
}
std::cout << std::endl;
}
}
void print_vec(short* v, const int n)
{
for (short i = 0; i < n; i++)
{
std::cout << v[i];
if (i != n - 1)
std::cout << " ";
}
}
连接文件mat_vec_mul.asm的代码
.686P
.model flat, C
.data
small_size = 2
ptr_size = 4
msize dw 0
nsize dw 0
.data?
i dw ?
.code
public mat_vec_mul
mat_vec_mul proc near
push ebp
mov ebp, esp
mat equ dword ptr [ebp+8]
vec equ dword ptr [ebp+12]
vec_r equ dword ptr [ebp+16]
m equ dword ptr [ebp+20]
n equ dword ptr [ebp+24]
xor ecx, ecx
xor eax, eax
mov eax, m
mov ecx, dword ptr ptr_size
imul ecx
mov dword ptr msize, eax
xor eax, eax
mov eax, n
mov ecx, dword ptr small_size
imul ecx
mov dword ptr nsize, eax
xor eax, eax
xor ecx, ecx
;mov ecx, m
xor ebx, ebx
mov ebx, mat
xor esi, esi
mov esi, vec_r
;xor edi, edi
;mov edi, vec
.repeat
mov dword ptr i, ecx
;mov eax, dword ptr [esi]
mov word ptr [esi], 0
xor edi, edi
mov edi, vec
xor ecx, ecx
.while (ecx < dword ptr nsize)
;ebx=i;ecx=j
mov eax, dword ptr [ebx]
mov ax, word ptr [eax+ecx]
mov dx, word ptr [edi]
;mov dx, word ptr [edx]
imul dx;dx:ax = mul
xor edx, edx
;mov edx, dword ptr [esi]
;mov [edx], ax
add word ptr [esi], ax
add ecx, small_size
add edi, small_size
.endw
mov ecx, dword ptr i
add ecx, ptr_size
;mov eax, dword ptr ptr_size
add esi, small_size
add ebx, ptr_size
xor eax, eax
.until (cx >= word ptr msize)
exit:
xor esi, esi
xor edi, edi
xor ecx, ecx
xor ebx, ebx
pop ebp
ret
mat_vec_mul endp
end
在 Release 的第 86 行，抛出了一个 nullptr 异常。vec_res 是空的，但一切都在调试中工作。
没有找到如何调用 QueryPerformanceCounter 函数。像这样试过。给出错误，不知道 BOOL 和 LARGE_INTEGER 是什么。
import core.sys.windows.windows;
import core.sys.windows.w32api;
import core.sys.windows.winbase;
pragma(lib, "kernel32");
extern (Windows)
{
BOOL QueryPerformanceCounter(LARGE_INTEGER *lpPerformanceCount);
}
void main()
{}
在我包含的 .dll 中找不到函数（funcPtr == 0）。我假设函数的名称在内部以某种方式被编码或更改，但我自己还无法弄清楚。
程序：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
namespace Lab1Dynamic
{
class Program
{
[DllImport("kernel32", SetLastError = true, CharSet = CharSet.Ansi)]
static extern IntPtr LoadLibrary([MarshalAs(UnmanagedType.LPStr)]string lpFileName);
[DllImport("kernel32", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)]
static extern IntPtr GetProcAddress(IntPtr hModule, string procName);
[DllImport("kernel32", SetLastError = true, EntryPoint = "GetProcAddress")]
static extern IntPtr GetProcAddressOrdinal(IntPtr hModule, IntPtr procName);
private delegate double fDelegate(double x, double y);
static void Main(string[] args)
{
var dllPath = "MyLibrary.dll";
IntPtr dllInstance = LoadLibrary(dllPath);
while (dllInstance == IntPtr.Zero)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("Can't load DLL " + dllPath);
Console.ForegroundColor = ConsoleColor.Gray;
Console.WriteLine("Write the path below...");
dllPath = Console.ReadLine();
dllInstance = LoadLibrary(dllPath);
}
string fname = "f";
IntPtr funcPtr = GetProcAddress(dllInstance, fname);
fDelegate fd = (fDelegate)Marshal.GetDelegateForFunctionPointer(funcPtr,
typeof(fDelegate));
var y = fd(1.0, 2.0);
}
}
}
dll：
using System;
namespace MyProj
{
public class MyLibrary
{
public static double f(double x, double y) => 3 * Math.Sin(x) + 2 * Math.Cos(y);
}
}
DLL（C++，VS2019）：MyLib.h：
#pragma once
extern "C" __declspec(dllexport) double f(const double x, const double y);
MyLib.cpp：
#include "MyLib.h"
#include "pch.h"
#include <cmath>
double f(const double x, const double y)
{
return 3 * sin(x) + 2 * cos(y);
}
PS根据MDSN的指南here
我从 Yandex 编写了一个简单的天气解析器，但如果温度为负，那么它会显示一个问号。尝试了很多东西，但到目前为止没有任何帮助。请帮忙。
代码（Python 3.7）
import urllib
from bs4 import BeautifulSoup
def ParseWeatherYandex(city):
url = 'https://yandex.ru/pogoda/' + city
page = urllib.request.urlopen(url).read()
soup = BeautifulSoup(page, 'html.parser')
#getting time now, temperature and condition
day = soup.find('time', 'fact__time').contents
temperature = soup.find('span', 'temp__value').contents
weather_type = soup.find('div', 'link__condition day-anchor i-bem').contents
#parsing feeling temperature
t = soup.find('dl', 'term term_orient_h fact__feels-like')
t = ((t.div).span).contents
#joining lists in one
feels = list(soup.find('dt', 'term__label').contents) + t
print(day[0] + '\n' + 'Температура сейчас: '+ (temperature[0]).center(3), end='\n')
print('Погода: %s' %weather_type[0], end=', ')
print('%s %s' %(feels[0].lower(), feels[1]))
ParseWeatherYandex(input())
input()
input()
我正在尝试将系列 1/sqrt(x+1) 扩展为泰勒级数。Wiki 说 sqrt(1+x) 的公式
因为 1/sqrt(x+1) = (sqrt(x+1))^-1，然后我试着把图中的分数翻转过来，数一下数列的项，结果发现公式是错误的。告诉我出了什么事。
需要动态分配120个对象，然后存储一个指向它们的指针向量。有没有人知道如何比现在做得更好（ps代码不能循环工作）？
int main()
{
std::vector<Customer*> customerList(120,nullptr);
std::shared_ptr<std::vector<Customer>> customers(new std::vector<Customer>(120));
for (auto i = 0;i<customers->size();i++)
{
customerList.push_back(&(customers->[i]));
}
//cout << customers->at(0);
return 0;
}
我们有一个向量vector<int> first，我们也有第二个向量vector<int> second。
有必要从第一个向量中删除第二个向量中包含的所有元素。我知道可以用2个周期在额头上解决它，但是如果您有任何想法，请提供帮助。
如何才能做到这一点？