update dir

const/funciton_const/condition1/condition1.cpp

@@ -0,0 +1,8 @@
+#include<iostream>
+using namespace std;
+
+
+int main(){
+    const int *ptr;
+    *ptr=10; //error
+}

const/funciton_const/condition1/condition2.cpp

@@ -0,0 +1,9 @@
+#include<iostream>
+using namespace std;
+
+
+int main(){
+    const int p = 10;
+    const void *vp = &p;
+    void *vp = &p; //error
+}

const/funciton_const/condition1/condition3.cpp

@@ -0,0 +1,12 @@
+#include<iostream>
+using namespace std;
+
+int main(){
+    const int *ptr;
+    int val = 3;
+    ptr = &val; //ok
+    int *ptr1 = &val;
+    *ptr1=4;
+    cout<<*ptr<<endl;
+
+}

const/funciton_const/condition2/condition1.cpp

@@ -0,0 +1,10 @@
+#include<iostream>
+using namespace std;
+int main(){
+
+    int num=0;
+    int * const ptr=&num; //const指针必须初始化！且const指针的值不能修改
+    int * t = &num;
+    *t = 1;
+    cout<<*ptr<<endl;
+}

const/funciton_const/condition2/condition2.cpp

@@ -0,0 +1,8 @@
+#include<iostream>
+using namespace std;
+int main(){
+
+    const int num=0;
+    int * const ptr=&num; //error! const int* -> int*
+    cout<<*ptr<<endl;
+}

const/funciton_const/condition2/condition3.cpp

@@ -0,0 +1,8 @@
+#include<iostream>
+using namespace std;
+int main(){
+
+    const int num=10;
+    const int * const ptr=&num; //error! const int* -> int*
+    cout<<*ptr<<endl;
+}

const/funciton_const/condition3/condition1.cpp

@@ -0,0 +1,10 @@
+#include<iostream>
+using namespace std;
+
+int main(){
+
+    const int p = 3;
+    const int * const ptr = &p;
+    cout<<*ptr<<endl;
+
+}