添加循环for的demo

base/fortest.cpp

@@ -0,0 +1,36 @@
+//
+// Created by nicemoe on 2021/8/7.
+//
+
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    double m[5] = {3.1, 4.5, 6.3, 7.6, 1.4};
+
+    //x是值复制 无法修改m数组
+    for (double x : m)
+    {
+        x++;
+    }
+    for (double x : m)
+    {
+        cout << x << "\t";
+    }
+    cout << endl;
+
+    //&x是引用可以真正修改m数组
+    for (double &x : m)
+    {
+        x++;
+    }
+    cout << endl;
+    for (double x : m)
+    {
+        cout << x << "\t";
+    }
+    cout << endl;
+    return 0;
+}