vc++中未解决的外部错误

Unresolved externals error in VC++

本文关键字：外部 错误 未解决 vc++      更新时间：2023-10-16

我正在学习vc++并使用代码检查内存的使用信息。这个程序给了我三个未解决的外部错误…

error LNK2019: unresolved external symbol _GetProcessMemoryInfo@12 referenced 
in function "void __cdecl PrintMemoryInfo(unsigned long)" 
(?PrintMemoryInfo@@YAXK@Z)
error LNK2019: unresolved external symbol _EnumProcesses@12 referenced in 
function _main
error LNK1120: 2 unresolved externals.

代码:

#include "stdafx.h"
#include <windows.h>
#include <stdio.h>
#include <psapi.h>
// To ensure correct resolution of symbols, add Psapi.lib to TARGETLIBS
// and compile with -DPSAPI_VERSION=1
void PrintMemoryInfo( DWORD processID )
{
    HANDLE hProcess;
    PROCESS_MEMORY_COUNTERS pmc;
    // Print the process identifier.
    printf( "nProcess ID: %un", processID );
    // Print information about the memory usage of the process.
    hProcess = OpenProcess(  PROCESS_QUERY_INFORMATION |
                                    PROCESS_VM_READ,
                                    FALSE, processID );
    if (NULL == hProcess)
        return;
    if ( GetProcessMemoryInfo( hProcess, &pmc, sizeof(pmc)) )
    {
        printf( "tPageFaultCount: 0x%08Xn", pmc.PageFaultCount );
        printf( "tPeakWorkingSetSize: 0x%08Xn", 
                  pmc.PeakWorkingSetSize );
        printf( "tWorkingSetSize: 0x%08Xn", pmc.WorkingSetSize );
        printf( "tQuotaPeakPagedPoolUsage: 0x%08Xn", 
                  pmc.QuotaPeakPagedPoolUsage );
        printf( "tQuotaPagedPoolUsage: 0x%08Xn", 
                  pmc.QuotaPagedPoolUsage );
        printf( "tQuotaPeakNonPagedPoolUsage: 0x%08Xn", 
                  pmc.QuotaPeakNonPagedPoolUsage );
        printf( "tQuotaNonPagedPoolUsage: 0x%08Xn", 
                  pmc.QuotaNonPagedPoolUsage );
        printf( "tPagefileUsage: 0x%08Xn", pmc.PagefileUsage ); 
        printf( "tPeakPagefileUsage: 0x%08Xn", 
                  pmc.PeakPagefileUsage );
    }
    CloseHandle( hProcess );
}
int main(void)
{
    // Get the list of process identifiers.
    DWORD aProcesses[1024], cbNeeded, cProcesses;
    unsigned int i;
    if ( !EnumProcesses( aProcesses, sizeof(aProcesses), &cbNeeded ) )
    {
        return 1;
    }
    // Calculate how many process identifiers were returned.
    cProcesses = cbNeeded / sizeof(DWORD);
    // Print the memory usage for each process
    for ( i = 0; i < cProcesses; i++ )
    {
        PrintMemoryInfo( aProcesses[i] );
    }
    return 0;
}

声明函数的头文件由编译器用来编译代码。不过，链接器确实需要定义所使用的外部函数。它通常在导入库中提供。错误信息告诉您链接器没有这样的定义。

您必须为psapi.h文件包含相应的库。

#pragma comment( lib, "psapi.lib" )

编辑::从msdn -备注部分，

为了保证符号的正确分辨率，需要添加Psapi。Lib to the使用-DPSAPI_VERSION=1编译程序。

额外::

#pragma comment是一个编译器指令，指示Visual c++在生成的目标文件中留下注释。当链接器处理目标文件时，可以读取注释。

#pragma comment(lib, libname)告诉链接器将'libname'库添加到库依赖列表中，就像您在Linker->Input->Additional dependencies的项目属性中添加了它一样

参见MSDN上的#pragma注释

尝试添加

#pragma comment(lib, “psapi.lib”)
相关文章：