diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
new file mode 100644
index 0000000..cea4d3f
--- /dev/null
+++ b/.vscode/c_cpp_properties.json
@@ -0,0 +1,18 @@
+{
+  "configurations": [
+    {
+      "name": "windows-gcc-x64",
+      "includePath": [
+        "${workspaceFolder}/**"
+      ],
+      "compilerPath": "gcc",
+      "cStandard": "${default}",
+      "cppStandard": "${default}",
+      "intelliSenseMode": "windows-gcc-x64",
+      "compilerArgs": [
+        ""
+      ]
+    }
+  ],
+  "version": 4
+}
\ No newline at end of file
diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..ad33348
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,24 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "C/C++ Runner: Debug Session",
+      "type": "cppdbg",
+      "request": "launch",
+      "args": [],
+      "stopAtEntry": false,
+      "externalConsole": true,
+      "cwd": "c:/Users/孟婷玉/Desktop/学生成绩管理系统/System",
+      "program": "c:/Users/孟婷玉/Desktop/学生成绩管理系统/System/build/Debug/outDebug",
+      "MIMode": "gdb",
+      "miDebuggerPath": "gdb",
+      "setupCommands": [
+        {
+          "description": "Enable pretty-printing for gdb",
+          "text": "-enable-pretty-printing",
+          "ignoreFailures": true
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..65c81b6
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,38 @@
+{
+  "C_Cpp_Runner.cCompilerPath": "gcc",
+  "C_Cpp_Runner.cppCompilerPath": "g++",
+  "C_Cpp_Runner.debuggerPath": "gdb",
+  "C_Cpp_Runner.cStandard": "",
+  "C_Cpp_Runner.cppStandard": "",
+  "C_Cpp_Runner.msvcBatchPath": "",
+  "C_Cpp_Runner.useMsvc": false,
+  "C_Cpp_Runner.warnings": [
+    "-Wall",
+    "-Wextra",
+    "-Wpedantic",
+    "-Wshadow",
+    "-Wformat=2",
+    "-Wconversion",
+    "-Wnull-dereference",
+    "-Wsign-conversion"
+  ],
+  "C_Cpp_Runner.enableWarnings": true,
+  "C_Cpp_Runner.warningsAsError": false,
+  "C_Cpp_Runner.compilerArgs": [],
+  "C_Cpp_Runner.linkerArgs": [],
+  "C_Cpp_Runner.includePaths": [],
+  "C_Cpp_Runner.includeSearch": [
+    "*",
+    "**/*"
+  ],
+  "C_Cpp_Runner.excludeSearch": [
+    "**/build",
+    "**/build/**",
+    "**/.*",
+    "**/.*/**",
+    "**/.vscode",
+    "**/.vscode/**"
+  ],
+  "C_Cpp_Runner.useAddressSanitizer": false,
+  "C_Cpp_Runner.showCompilationTime": false
+}
\ No newline at end of file
diff --git a/4.md b/4.md
new file mode 100644
index 0000000..a56f960
--- /dev/null
+++ b/4.md
@@ -0,0 +1,24 @@
+//4 函数功能：按选择法将数组sum的元素值排序 
+void SortbyScore(STU stu[],int n,int m,int (*compare)(float a,float b))
+{
+	int  i, j, k, t;
+	for (i=0; i<n-1; i++)
+	{
+		k = i;
+		for (j=i+1; j<n; j++)
+		{
+			if ((*compare)(stu[j].sum, stu[k].sum)) k = j;
+		}
+		if (k != i)
+		{		   
+		   for (t=0; t<m; t++)             // 交换m门课程的成绩 
+            {
+                SwapFloat(&stu[k].score[t], &stu[i].score[t]);
+            }
+SwapFloat(&stu[k].sum, &stu[i].sum);    // 交换总分 
+SwapFloat(&stu[k].aver, &stu[i].aver); // 交换平均分   
+SwapLong(&stu[k].num, &stu[i].num);     // 交换学号 
+SwapChar(stu[k].name, stu[i].name);     // 交换姓名 
+		}
+	}
+}
\ No newline at end of file