这是我在vi中的示例文件
1./*
2. * C Program to Build Binary Tree if Inorder or Postorder Traversal as Input
3. *
4. * 40
5. * / \
6. * 20 60
7. * / \ \
8. * 10 30 80
9. * \
10. * 90
11. * (Given Binary Search Tree)
12. */
13.#include <stdio.h>
14.#include <stdlib.h>
15.
16.struct btnode
17.{
18. int value;
19. struct btnode *l;
20. struct btnode *r;
21.}*root = NULL, *temp = NULL;
22.
23.typedef struct btnode N;
24.void insert();
25.N* bt(int arr[],int,int);
26.N* new(int);
27.void inorder(N *t);
28.void create();
29.void search(N *t);
30.void preorder(N *t);
31.void postorder(N *t);
32.
33.void main()
34.{
35. int ch, i, n;
36. int arr[] = {10, 20, 30, 40, 60, 80, 90};
37. n = sizeof(arr) / sizeof(arr[0]);
38.
39. printf("\n1- Inorder\n");
40. printf("2 - postorder\n");
41. printf("\nEnter choice : ");
42. scanf("%d", &ch);
43. switch (ch)
44. {
45. case 1:
46. root = bt(arr, 0, n-1);
47. printf("Given inorder traversal as input\n");
48. for (i = 0;i< = 6;i++)
49. printf("%d->", arr[i]);
50. printf("\npreorder traversal of tree\n");
51. preorder(root);
52. printf("\ninorder traversal of tree\n");
53. inorder(root);
54. printf("\npostorder traversal of tree\n");
55. postorder(root);
56. break;
57. case 2:
58. insert();
59. printf("\npreorder traversal of tree\n");
60. preorder(root);
61. printf("\nInorder traversal of tree\n");
62. inorder(root);
63. printf("\npostorder traversal of tree\n");
64. postorder(root);
65. break;
66. default:printf("enter correct choice");
67. }
68.}
69.
70./* To create a new node */
71.N* new(int val)
72.{
73. N* node = (N*)malloc(sizeof(N));
74.
75. node->value = val;
76. node->l = NULL;
77. node->r = NULL;
78. return node;
79.}
80.
81./* To create a balanced binary search tree */
82.N* bt(int arr[], int first, int last)
83.{
84. int mid;
85.
86. N* root = (N*)malloc(sizeof(N));
87. if (first > last)
88. return NULL;
89. mid = (first + last) / 2;
90. root = new(arr[mid]);
91. root->l = bt(arr, first, mid - 1);
92. root->r = bt(arr, mid + 1, last);
93. return root;
94.}
95.
96./* Insert a node in the tree */
97.void insert()
98.{
99. int arr1[] = {10, 30, 20, 90, 80, 60, 40}, i;
100.
101. printf("Given post order traversal array\n");
102. for (i = 0;i <= 6;i++)
103. {
104. printf("%d->", arr1[i]);
105. }
106. for (i = 6;i >= 0;i--)
107. {
108. create(arr1[i]);
109. if (root = = NULL)
110. root = temp;
111. else
112. search(root);
113. }
114.}
115.
116./*Create a node */
117.void create(int data)
118.{
119. temp = (N *)malloc(1*sizeof(N));
120.
121. temp->value = data;
122. temp->l = temp->r = NULL;
123.}
124.
125./* Search for the appropriate position to insert the new node */
126.void search(N *t)
127.{
128. if ((temp->value>t->value)&&(t->r != NULL))
129. search(t->r);
130. else if ((temp->value>t->value)&&(t->r == NULL))
131. t->r = temp;
132. else if ((temp->value<t->value)&&(t->l != NULL))
133. search(t->l);
134. else if ((temp->value<t->value)&&(t->l == NULL))
135. t->l = temp;
136.}
137.
138./* to display inorder of tree */
139.void inorder(N *t)
140.{
141. if (t->l != NULL)
142. inorder(t->l);
143. printf("%d->", t->value);
144. if (t->r != NULL)
145. inorder(t->r);
146.}
147.
148./* to display preorder traversal of tree */
149.void preorder(N *t)
150.{
151. printf("%d->", t->value);
152. if (t->l != NULL)
153. inorder(t->l);
154. if (t->r != NULL)
155. inorder(t->r);
156.}
157.
158./* to display postorder traversal of tree */
159.void postorder(N *t)
160.{
161. if (t->l != NULL)
162. inorder(t->l);
163. if (t->r != NULL)
164. inorder(t->r);
165. printf("%d->", t->value);
166.}
在上面的代码中，用vi中的空格替换数字的正确正则表达式是什么。 我想用vi中的空格替换行号。 我在网上搜索了各种教程，将行号放入文件中，但是如果行号已经存在，该如何替换呢？
答案 0 :(得分：6)
您可以使用以下替换：
:%s/^\d\+\./ /
其中
^ 匹配行的开头\d\+ 匹配一个或多个数字\. 匹配一个点/ / 替换为空格答案 1 :(得分：2)
一个简单的命令可以解决您的问题：
:%norm df.
: .................. command mode
% .................. whole file
norm ............... normal mode
df. ................ delete until the first dot
答案 2 :(得分：0)
考虑到所有行的开头都有一个数字，这会删除它并加上点：
:%s/\d*.
如果您确实希望将其替换为空格，请使用：
:%s/\d*./ /