diff --git a/Chapter7/C7-函数.md b/Chapter7/C7-函数.md
new file mode 100644
index 0000000..45fdb39
--- /dev/null
+++ b/Chapter7/C7-函数.md
@@ -0,0 +1,556 @@
+# 目录
+- [目录](#目录)
+- [函数](#函数)
+  - [函数的定义](#函数的定义)
+  - [函数的传参](#函数的传参)
+  - [函数的调用](#函数的调用)
+    - [嵌套调用](#嵌套调用)
+    - [递归调用](#递归调用)
+  - [函数与数组](#函数与数组)
+    - [一维数组](#一维数组)
+    - [二维数组](#二维数组)
+    - [字符数组](#字符数组)
+  - [函数与指针](#函数与指针)
+    - [指针函数](#指针函数)
+    - [函数指针](#函数指针)
+    - [函数指针数组](#函数指针数组)
+    - [指向指针函数的函数指针数组](#指向指针函数的函数指针数组)
+
+
+# 函数
+
+## 函数的定义
+
+数据类型  函数名 （ 【数据类型 形参名，数据类型 形参，...】 ）
+
+
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+
+    printf("argc = %d\n", argc);
+    // 输出传入参数的个数
+
+    // for (int i = 0; i < argc; i++) puts(argv[i]);
+
+    for (int i = 0; argv[i] != NULL; i++) puts(argv[i]);
+
+    // printf("Hello!\n");
+
+    exit(0);
+}
+```
+
+
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+void print_hello(void);
+
+// 主调函数
+int main()
+{
+    print_hello();
+
+    exit(0);
+}
+
+// 被调函数
+void print_hello(void)
+{
+    printf("Hello world!\n");
+
+    return;
+}
+```
+
+
+
+## 函数的传参
+
+值传递
+
+地址传递
+
+全局变量传参
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+#if 0
+int print_value(int a, int b)
+{
+    printf("%d %d\n", a, b);
+    return 0;
+}
+#endif
+
+// void swap(int i, int j)
+// {
+//     int tmp;
+
+//     tmp = i;
+//     i   = j;
+//     j   = tmp;
+// }
+
+void swap(int *p, int *q)
+{
+    int tmp;
+
+    tmp = *p;
+    *p  = *q;
+    *q  = tmp;
+}
+int main()
+{
+    int i = 3, j = 5;
+
+    // swap(i, j);
+    // 实际没有交换
+
+    swap(&i, &j);
+
+    printf("%d %d\n", i, j);
+
+
+    // print_value(i, j);
+
+    exit(0);
+}
+```
+
+
+
+
+
+## 函数的调用
+
+### 嵌套调用
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+int max(int a, int b, int c)
+{
+    int tmp;
+    tmp = a > b ? a : b;
+
+    return tmp > c ? tmp : c;
+}
+
+int min(int a, int b, int c)
+{
+    int tmp;
+    tmp = a < b ? a : b;
+
+    return tmp < c ? tmp : c;
+}
+
+int dist(int a, int b, int c)
+{
+    return max(a, b, c) - min(a, b, c);
+}
+
+int main()
+{
+    int a = 3, b = 5, c = 10;
+
+    printf("result = %d\n", dist(a, b, c));
+
+    exit(0);
+}
+```
+
+
+
+### 递归调用
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+void c(void)
+{
+    printf("[%s]begin!\n", __FUNCTION__);
+    printf("[%s]end!\n", __FUNCTION__);
+}
+
+void b(void)
+{
+    printf("[%s]begin!\n", __FUNCTION__);
+    printf("[%s]call c()!\n", __FUNCTION__);
+    c();
+    printf("[%s]c() returned!\n", __FUNCTION__);
+    printf("[%s]end!\n", __FUNCTION__);
+}
+
+void a(void)
+{
+    printf("[%s]begin!\n", __FUNCTION__);
+    printf("[%s]call b()!\n", __FUNCTION__);
+    b();
+    printf("[%s]b() returned!\n", __FUNCTION__);
+    printf("[%s]end!\n", __FUNCTION__);
+}
+
+int main()
+{
+    printf("[%s]begin!\n", __FUNCTION__);
+    printf("[%s]call a()!\n", __FUNCTION__);
+    a();
+    printf("[%s]a() returned!\n", __FUNCTION__);
+    printf("[%s]end!\n", __FUNCTION__);
+    // out:
+    // [main]begin!
+    // [main]call a()!
+    // [a]begin!
+    // [a]call b()!
+    // [b]begin!
+    // [b]call c()!
+    // [c]begin!
+    // [c]end!
+    // [b]c() returned!
+    // [b]end!
+    // [a]b() returned!
+    // [a]end!
+    // [main]a() returned!
+    // [main]end!
+
+    exit(0);
+}
+```
+
+
+
+
+
+## 函数与数组
+
+### 一维数组
+
+```c
+int a[N] = {1,2,3,4,5,6};
+int *p = a;
+```
+
+| 传参  | 类型  |
+| ----- | ----- |
+| a     | int * |
+| *a    | int   |
+| a[0]  | int   |
+| &a[3] | int * |
+| p[i]  | int   |
+| p     | int * |
+| *p    | int   |
+| p+1   | int*  |
+
+
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+void print_arr(int *p, int size)
+{
+    int i;
+    printf("%s:%d\n", __FUNCTION__, sizeof(p));
+    // out: 8 指针
+
+    for (i = 0; i < size; i++) printf("%d ", *(p + i));
+    printf("\n");
+}
+
+
+void func(int *p, int size)
+{
+    int *tmp;
+
+    for (int i = 0; i < size / 2; i++)
+    {
+        *tmp                = *(p + i);
+        *(p + i)            = *(p + size - 1 - i);
+        *(p + size - 1 - i) = *tmp;
+    }
+}
+
+int main()
+{
+    int a[] = {1, 3, 5, 7, 9};
+
+    // printf("%s:%d\n", __FUNCTION__, sizeof(a));
+    // out: 20 5*4
+
+    // print_arr(a, sizeof(a) / sizeof(*a));
+
+
+    for (int i = 0; i < sizeof(a) / sizeof(*a); i++)
+    {
+        printf("%d ", a[i]);
+    }
+    printf("\n");
+
+    func(a, sizeof(a) / sizeof(*a));
+
+    for (int i = 0; i < sizeof(a) / sizeof(*a); i++)
+    {
+        printf("%d ", a[i]);
+    }
+    printf("\n");
+
+    exit(0);
+}
+```
+
+
+
+### 二维数组
+
+```c
+int a[M][N]={...};
+
+int *p = *a;
+// p 是指向数组第一行的第一个元素的指针，等价于 &a[0][0]。
+// 列指针
+
+int (*q)[N] = a;
+// q 是指向由 N 个 int 组成的数组的指针，即指向二维数组每一行的指针
+// 行指针
+```
+
+
+
+| 传参                       | 类型                                   |
+| -------------------------- | -------------------------------------- |
+| `a[i][j]`                  | int                                    |
+| `*(a+i)+j`                 | int *                                  |
+| `a[i]+j`    等同于*(a+i)+j | ~~int~~  正确答案： int *              |
+| `p[i]`                     | ~~int [N] *~~ 正确答案： int           |
+| `*p`                       | ~~int [N] *~~ 正确答案： int           |
+| `q[i][j]`                  | int                                    |
+| `*q`                       | ~~int [N] *~~   正确答案： int *       |
+| `q`                        | int (*) [N]                            |
+| `p+3`                      | ~~int [N] *~~  正确答案： int *        |
+| `q+2`                      | ~~int [N] *~~   正确答案： int (*) [N] |
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+#define M 3
+#define N 4
+
+void print_douarr(int *p, int n)
+{
+    int i, j;
+
+    for (i = 0; i < n; i++)
+    {
+        printf("%d ", *(p + i));
+    }
+    printf("\n");
+}
+
+// void print_douarr1(int (*p)[N], int m, int n)
+void print_douarr1(int (*p)[N], int m, int n)
+{
+    printf("sizeof(p)=%d\n", sizeof(p));
+
+    int i, j;
+
+    for (i = 0; i < m; i++)
+    {
+        for (j = 0; j < n; j++)
+        {
+            // printf("%4d", *(*(p + i) + j));
+            printf("%4d", p[i][j]);
+        }
+        printf("\n");
+    }
+}
+
+float average_score(int *p, int n)
+{
+    float sum = 0;
+
+    for (int i = 0; i < n; i++)
+    {
+        sum += *(p + i);
+    }
+
+    return sum / n;
+}
+
+
+void find_num(int (*p)[N], int num)
+{
+    for (int i = 0; i < N; i++)
+    {
+        printf("%d ", *(*(p + num) + i));
+    }
+    printf("\n");
+}
+
+int main()
+{
+    int i, j;
+    int a[M][N] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
+
+    float ave;
+
+    // ave = average_score(*a, M * N);
+    // printf("ave = %f\n", ave);
+
+    find_num(a, 2);
+
+
+    // print_douarr(&a[0][0], M * N);
+
+    // printf("sizeof(a)=%d\n", sizeof(a));
+    // print_douarr1(a, M, N);
+
+    exit(0);
+}
+```
+
+
+
+
+
+### 字符数组
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+
+char *mystrcpy(char *dest, const char *src)
+{
+    char *ret = dest;
+    if (NULL != dest && NULL != src)
+        while ((*dest++ = *src++) != '\0')
+            ;
+
+    return ret;
+}
+
+char *mystrncpy(char *dest, const char *src, size_t n)
+{
+    int i;
+    for (i = 0; i < n && (dest[i] = src[i]); i++)
+        ;
+
+    for (; i < n; i++)
+        dest[i] = '\0';
+
+    return dest;
+}
+
+
+int main()
+{
+    char str1[] = "helloworld";
+    char str2[128];
+
+    // mystrcpy(str2, str1);
+
+    mystrncpy(str2, str1, 5);
+
+    puts(str2);
+
+    exit(0);
+}
+```
+
+
+
+
+
+## 函数与指针
+
+### 指针函数
+
+是一个**函数**，返回值是**指针**。
+
+返回值  *  函数名  （形参）
+
+如：`int * fun(int);`
+
+
+
+### 函数指针
+
+是一个**指针**，指向**函数**。
+
+类型  （* 指针名） （形参）
+
+如： `int (*p)(int);`
+
+
+
+### 函数指针数组
+
+由**函数指针**组成的数组。
+
+类型  （*数组名【下标】） （形参）
+
+如： `int (*arr[N])(int);`
+
+
+
+### 指向指针函数的函数指针数组
+
+`int *(*funcp[N])(int)`
+
+
+
+```c
+#include <stdio.h>
+#include <stdlib.h>
+
+int add(int a, int b)
+{
+    return a + b;
+}
+
+int sub(int a, int b)
+{
+    return a - b;
+}
+
+int main()
+{
+    int a = 3, b = 5;
+    int ret;
+    // int (*p)(int, int);
+    // int (*q)(int, int);
+
+    int (*funcp[2])(int, int);
+
+    // p = add;
+    // q = sub;
+
+    funcp[0] = add;
+    funcp[1] = sub;
+
+    // ret = p(a, b);
+    // ret = q(a, b);
+
+    for (int i = 0; i < 2; i++)
+    {
+        ret = funcp[i](a, b);
+        printf("ret = %d\n", ret);
+    }
+
+    exit(0);
+}
+```
+
diff --git a/Chapter7/arr.c b/Chapter7/arr.c
new file mode 100644
index 0000000..98429fc
--- /dev/null
+++ b/Chapter7/arr.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void print_arr(int *p, int size)
+{
+    int i;
+    printf("%s:%d\n", __FUNCTION__, sizeof(p));
+    // out: 8 指针
+
+    for (i = 0; i < size; i++) printf("%d ", *(p + i));
+    printf("\n");
+}
+
+
+void func(int *p, int size)
+{
+    int *tmp;
+
+    for (int i = 0; i < size / 2; i++)
+    {
+        *tmp                = *(p + i);
+        *(p + i)            = *(p + size - 1 - i);
+        *(p + size - 1 - i) = *tmp;
+    }
+}
+
+int main()
+{
+    int a[] = {1, 3, 5, 7, 9};
+
+    // printf("%s:%d\n", __FUNCTION__, sizeof(a));
+    // out: 20 5*4
+
+    // print_arr(a, sizeof(a) / sizeof(*a));
+
+
+    for (int i = 0; i < sizeof(a) / sizeof(*a); i++)
+    {
+        printf("%d ", a[i]);
+    }
+    printf("\n");
+
+    func(a, sizeof(a) / sizeof(*a));
+
+    for (int i = 0; i < sizeof(a) / sizeof(*a); i++)
+    {
+        printf("%d ", a[i]);
+    }
+    printf("\n");
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter7/chararr.c b/Chapter7/chararr.c
new file mode 100644
index 0000000..f2c0303
--- /dev/null
+++ b/Chapter7/chararr.c
@@ -0,0 +1,40 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+
+char *mystrcpy(char *dest, const char *src)
+{
+    char *ret = dest;
+    if (NULL != dest && NULL != src)
+        while ((*dest++ = *src++) != '\0')
+            ;
+
+    return ret;
+}
+
+char *mystrncpy(char *dest, const char *src, size_t n)
+{
+    int i;
+    for (i = 0; i < n && (dest[i] = src[i]); i++)
+        ;
+
+    for (; i < n; i++)
+        dest[i] = '\0';
+
+    return dest;
+}
+
+
+int main()
+{
+    char str1[] = "helloworld";
+    char str2[128];
+
+    // mystrcpy(str2, str1);
+
+    mystrncpy(str2, str1, 5);
+
+    puts(str2);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter7/douarr.c b/Chapter7/douarr.c
new file mode 100644
index 0000000..4c51e50
--- /dev/null
+++ b/Chapter7/douarr.c
@@ -0,0 +1,102 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define M 3
+#define N 4
+
+void print_douarr(int *p, int n)
+{
+    int i, j;
+
+    for (i = 0; i < n; i++)
+    {
+        printf("%d ", *(p + i));
+    }
+    printf("\n");
+}
+
+// void print_douarr1(int (*p)[N], int m, int n)
+void print_douarr1(int (*p)[N], int m, int n)
+{
+    printf("sizeof(p)=%d\n", sizeof(p));
+
+    int i, j;
+
+    for (i = 0; i < m; i++)
+    {
+        for (j = 0; j < n; j++)
+        {
+            // printf("%4d", *(*(p + i) + j));
+            printf("%4d", p[i][j]);
+        }
+        printf("\n");
+    }
+}
+
+float average_score(int *p, int n)
+{
+    float sum = 0;
+
+    for (int i = 0; i < n; i++)
+    {
+        sum += *(p + i);
+    }
+
+    return sum / n;
+}
+
+
+#if 0
+void find_num(int (*p)[N], int num)
+{
+    for (int i = 0; i < N; i++)
+    {
+        printf("%d ", *(*(p + num) + i));
+    }
+    printf("\n");
+}
+#endif
+
+int *find_num(int (*p)[N], int num)
+{
+    if (num > M - 1)
+        return NULL;
+    return *(p + num);
+}
+
+int main()
+{
+    int i, j;
+    int a[M][N] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
+
+    float ave;
+
+    // ave = average_score(*a, M * N);
+    // printf("ave = %f\n", ave);
+
+    // find_num(a, 2);
+
+    int *res;
+
+    res = find_num(a, 2);
+    if (NULL != res)
+    {
+        for (i = 0; i < N; i++)
+        {
+            printf("%d ", res[i]);
+        }
+        printf("\n");
+    }
+    else
+    {
+        printf("Can not find!\n");
+    }
+
+
+    // print_douarr(&a[0][0], M * N);
+
+    // printf("sizeof(a)=%d\n", sizeof(a));
+    // print_douarr1(a, M, N);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter7/fun_point.c b/Chapter7/fun_point.c
new file mode 100644
index 0000000..67c92f3
--- /dev/null
+++ b/Chapter7/fun_point.c
@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int add(int a, int b)
+{
+    return a + b;
+}
+
+int sub(int a, int b)
+{
+    return a - b;
+}
+
+int main()
+{
+    int a = 3, b = 5;
+    int ret;
+    // int (*p)(int, int);
+    // int (*q)(int, int);
+
+    int (*funcp[2])(int, int);
+
+    // p = add;
+    // q = sub;
+
+    funcp[0] = add;
+    funcp[1] = sub;
+
+    // ret = p(a, b);
+    // ret = q(a, b);
+
+    for (int i = 0; i < 2; i++)
+    {
+        ret = funcp[i](a, b);
+        printf("ret = %d\n", ret);
+    }
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter7/func.c b/Chapter7/func.c
new file mode 100644
index 0000000..443c393
--- /dev/null
+++ b/Chapter7/func.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void c(void)
+{
+    printf("[%s]begin!\n", __FUNCTION__);
+    printf("[%s]end!\n", __FUNCTION__);
+}
+
+void b(void)
+{
+    printf("[%s]begin!\n", __FUNCTION__);
+    printf("[%s]call c()!\n", __FUNCTION__);
+    c();
+    printf("[%s]c() returned!\n", __FUNCTION__);
+    printf("[%s]end!\n", __FUNCTION__);
+}
+
+void a(void)
+{
+    printf("[%s]begin!\n", __FUNCTION__);
+    printf("[%s]call b()!\n", __FUNCTION__);
+    b();
+    printf("[%s]b() returned!\n", __FUNCTION__);
+    printf("[%s]end!\n", __FUNCTION__);
+}
+
+int main()
+{
+    printf("[%s]begin!\n", __FUNCTION__);
+    printf("[%s]call a()!\n", __FUNCTION__);
+    a();
+    printf("[%s]a() returned!\n", __FUNCTION__);
+    printf("[%s]end!\n", __FUNCTION__);
+    // out:
+    // [main]begin!
+    // [main]call a()!
+    // [a]begin!
+    // [a]call b()!
+    // [b]begin!
+    // [b]call c()!
+    // [c]begin!
+    // [c]end!
+    // [b]c() returned!
+    // [b]end!
+    // [a]b() returned!
+    // [a]end!
+    // [main]a() returned!
+    // [main]end!
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter7/hello.c b/Chapter7/hello.c
new file mode 100644
index 0000000..c7e543c
--- /dev/null
+++ b/Chapter7/hello.c
@@ -0,0 +1,20 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void print_hello(void);
+
+// 主调函数
+int main()
+{
+    print_hello();
+
+    exit(0);
+}
+
+// 被调函数
+void print_hello(void)
+{
+    printf("Hello world!\n");
+
+    return;
+}
\ No newline at end of file
diff --git a/Chapter7/main.c b/Chapter7/main.c
new file mode 100644
index 0000000..e4af4b7
--- /dev/null
+++ b/Chapter7/main.c
@@ -0,0 +1,17 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+
+    printf("argc = %d\n", argc);
+    // 输出传入参数的个数
+
+    // for (int i = 0; i < argc; i++) puts(argv[i]);
+
+    for (int i = 0; argv[i] != NULL; i++) puts(argv[i]);
+
+    // printf("Hello!\n");
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter7/min_max.c b/Chapter7/min_max.c
new file mode 100644
index 0000000..912bf6e
--- /dev/null
+++ b/Chapter7/min_max.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int max(int a, int b, int c)
+{
+    int tmp;
+    tmp = a > b ? a : b;
+
+    return tmp > c ? tmp : c;
+}
+
+int min(int a, int b, int c)
+{
+    int tmp;
+    tmp = a < b ? a : b;
+
+    return tmp < c ? tmp : c;
+}
+
+int dist(int a, int b, int c)
+{
+    return max(a, b, c) - min(a, b, c);
+}
+
+int main()
+{
+    int a = 3, b = 5, c = 10;
+
+    printf("result = %d\n", dist(a, b, c));
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter7/swap.c b/Chapter7/swap.c
new file mode 100644
index 0000000..edd1b38
--- /dev/null
+++ b/Chapter7/swap.c
@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#if 0
+int print_value(int a, int b)
+{
+    printf("%d %d\n", a, b);
+    return 0;
+}
+#endif
+
+// void swap(int i, int j)
+// {
+//     int tmp;
+
+//     tmp = i;
+//     i   = j;
+//     j   = tmp;
+// }
+
+void swap(int *p, int *q)
+{
+    int tmp;
+
+    tmp = *p;
+    *p  = *q;
+    *q  = tmp;
+}
+int main()
+{
+    int i = 3, j = 5;
+
+    // swap(i, j);
+    // 实际没有交换
+
+    swap(&i, &j);
+
+    printf("%d %d\n", i, j);
+
+
+    // print_value(i, j);
+
+    exit(0);
+}
\ No newline at end of file