Question

所以我打开了一个CSV文件，并将其添加到结构中。我现在想按结构的U值（从最低到最高）对结构进行排序。我所做的工作有些奏效，但它交换的是交换的值，例如x和y，但这些交换的值并不意味着要交换，但仍按U排序。我的结构-

typedef struct {
    float xvalue;
    float yvalue;
    float uvalue;
    float vvalue;
} flow_data;

int num_compare(const void *v1, const void *v2)
{
    const flow_data *p1 = (flow_data *)v1;
    const flow_data *p2 = (flow_data *)v2;
    if (p1->uvalue < p2->uvalue)
        return -1;
    else if (p1->uvalue > p2->uvalue)
        return +1;
    else
        return 0;
}

我在哪里运行代码-

FILE* fp = fopen(flow_file, "r");

// Checking if the file has been read succesfully
if( fp == NULL)
{
    perror("Error opening file");
    exit(1);
}

char buf[500];
fgets(buf, sizeof(buf), fp); // Skip the first line

int total = 0;
flow_data d;
flow_data* dataset = NULL;

while(4 == fscanf(fp, "%f, %f, %f, %f\n", &d.xvalue, &d.yvalue, &d.uvalue, &d.vvalue))
{
    dataset = realloc(dataset, sizeof(*dataset) * (total + 1));
    dataset[total] = d;
    total++;
}

qsort(dataset, total, sizeof(dataset), num_compare);

Answer 1

更改

activate

收件人

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.2.0-preview1-35029" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="2.2.0-preview1-35029" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.2.0-preview1-35029" />
    <PackageReference Include="Microsoft.Extensions.Identity.Stores" Version="2.2.0-preview1-35029" />
    <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="2.1.1" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\Common\Common.csproj" />
    <ProjectReference Include="..\Database.Entities\Database.Entities.csproj" />
  </ItemGroup>

  <ItemGroup>
    <DotNetCliToolReference 
        Include="Microsoft.EntityFrameworkCore.Tools" 
        Version="2.0.0" />
    <DotNetCliToolReference 
        Include="Microsoft.EntityFrameworkCore.Tools.DotNet" 
        Version="2.0.0" /> 
  </ItemGroup>

  <ItemGroup>
    <Reference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore">
      <HintPath>..\..\..\..\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.aspnetcore.identity.entityframeworkcore\2.0.3\lib\netstandard2.0\Microsoft.AspNetCore.Identity.EntityFrameworkCore.dll</HintPath>
    </Reference>
  </ItemGroup>

</Project>

或

qsort(dataset, total, sizeof(dataset), num_compare);

因为指针的大小并不总是与结构的大小相同。

Qsorting结构的问题

1 个答案: