vscode c++ undefined reference to

方法1：

在task.json的"args": "-g後面添加

{
    "tasks": [
        {
            "type": "shell",
            "label": "C/C++: g++ build active file",
            "command": "/usr/bin/g++",
            "args": [
                "-g",
                "/media/F/U/cpp/ubuntu_vscode_demo1/apue.3e/lib/tellwait.c",//此處加入缺少的c檔案
                "/media/F/U/cpp/ubuntu_vscode_demo1/apue.3e/lib/error.c",
                "${file}",
                "-o",
                "${fileDirname}/${fileBasenameNoExtension}"
            ],
            "options": {
                "cwd": "${workspaceFolder}"
            },
            "problemMatcher": [
                "$gcc"
            ],
            "group": {
                "kind": "build",
                "isDefault": true
            }
        }
    ],
    "version": "2.0.0"
}
           

方法2：

c_cpp_properties.json

{
    "configurations": [
        {
            "name": "Linux",
            "includePath": [
                "${workspaceFolder}/**"
               //此處添加include的頭檔案
            ],
            "defines": [],
            "compilerPath": "/usr/bin/gcc",
            "cStandard": "gnu11",
            "cppStandard": "gnu++14",
            "intelliSenseMode": "gcc-x64"
        }
    ],
    "version": 4
}