分支操作创建另一条线路开发。它是有用的，当有人想开发过程叉成两个不同的方向。让我们假设发布的产品版本1.0中，可能要创建新的分支，所以可以保持独立，发展2.01.0 bug修复。
在本节中，我们将看到如何创建，遍历和合并分支。Jerry 已经沮丧，因为冲突，所以他决定创建新的私有分支。
[jerry@CentOS project_repo]$ ls branches tags trunk [jerry@CentOS project_repo]$ svn copy trunk branches/jerry_branch A branches/jerry_branch [jerry@CentOS project_repo]$ svn status A + branches/jerry_branch [jerry@CentOS project_repo]$ svn commit -m "Jerry's private branch" Adding branches/jerry_branch Adding branches/jerry_branch/README Committed revision 9. [jerry@CentOS project_repo]$
Jerry 是在他的私人分支工作。他补充说数组的排序操作。Jerry 修改后的代码看起来是这样的。
[jerry@CentOS project_repo]$ cd branches/jerry_branch/ [jerry@CentOS jerry_branch]$ cat array.c
上面的命令将产生以下结果
#include <stdio.h> #define MAX 16 void bubble_sort(int *arr, int n) { int i, j, temp, flag = 1; for (i = 1; i < n && flag == 1; ++i) { flag = 0; for (j = 0; j < n - i; ++j) { if (arr[j] > arr[j + 1]) { flag = 1; temp = arr[j]; arr[j] = arr[j + 1]; arr[j + 1] = temp; } } } } void accept_input(int *arr, int n) { int i; for (i = 0; i < n; ++i) scanf("%d", &arr[i]); } void display(int *arr, int n) { int i; for (i = 0; i < n; ++i) printf("|%d| ", arr[i]); printf(" "); } int main(void) { int i, n, key, ret, arr[MAX]; printf("Enter the total number of elements: "); scanf("%d", &n); /* Error handling for array overflow */ if (n >MAX) { fprintf(stderr, "Number of elements must be less than %d ", MAX); return 1; } printf("Enter the elements "); accept_input(arr, n); printf("Array has following elements "); display(arr, n); printf("Sorted data is "); bubble_sort(arr, n); display(arr, n); return 0; }
Jerry 编译并测试自己的代码和准备提交他修改的变化。
[jerry@CentOS jerry_branch]$ make array cc array.c -o array [jerry@CentOS jerry_branch]$ ./array
上面的命令将产生以下结果
Enter the total number of elements: 5 Enter the elements 10 -4 2 7 9 Array has following elements |10| |-4| |2| |7| |9| Sorted data is |-4| |2| |7| |9| |10| [jerry@CentOS jerry_branch]$ svn status ? array M array.c [jerry@CentOS jerry_branch]$ svn commit -m "Added sort operation" Sending jerry_branch/array.c Transmitting file data . Committed revision 10.
同时通过躯干，Tom决定执行搜索操作。Tom搜索操作添加代码，他的代码看起来像这样。
[tom@CentOS trunk]$ svn diff
上面的命令将产生以下结果
Index: array.c
===================================================================
--- array.c (revision 10)
+++ array.c (working copy)
@@ -2,6 +2,27 @@
#define MAX 16
+int bin_search(int *arr, int n, int key)
+{
+ int low, high, mid;
+
+ low = 0;
+ high = n - 1;
+ mid = low + (high - low) / 2;
+
+ while (low <= high) {
+ if (arr[mid] == key)
+ return mid;
+ if (arr[mid] > key)
+ high = mid - 1;
+ else
+ low = mid + 1;
+ mid = low + (high - low) / 2;
+ }
+
+ return -1;
+}
+
void accept_input(int *arr, int n)
{
int i;
@@ -22,7 +43,7 @@
int main(void)
{
- int i, n, arr[MAX];
+ int i, n, ret, key, arr[MAX];
printf("Enter the total number of elements: ");
scanf("%d", &n);
@@ -39,5 +60,16 @@
printf("Array has following elements
");
display(arr, n);
+ printf("Enter the element to be searched: ");
+ scanf("%d", &key);
+
+ ret = bin_search(arr, n, key);
+ if (ret < 0) {
+ fprintf(stderr, "%d element not present in array
", key);
+ return 1;
+ }
+
+ printf("%d element found at location %d
", key, ret + 1);
+
return 0;
}
审查后，他提交了他修改的变化。
[tom@CentOS trunk]$ svn status ? array M array.c [tom@CentOS trunk]$ svn commit -m "Added search operation" Sending trunk/array.c Transmitting file data . Committed revision 11.
但Tom 好奇为什么 Jerry 一直在做他的私人分支。
[tom@CentOS trunk]$ cd ../branches/ [tom@CentOS branches]$ svn up A jerry_branch A jerry_branch/array.c A jerry_branch/README [tom@CentOS branches]$ svn log ------------------------------------------------------------------------ r9 | jerry | 2013-08-27 21:56:51 +0530 (Tue, 27 Aug 2013) | 1 line Added sort operation ------------------------------------------------------------------------
查看Subversion的日志消息，Tom发现，Jerry实现的排序操作。Tom执行搜索操作使用二进制搜索算法，它总是希望数据的排序顺序。但是，如果用户提供的数据，未排序的顺序呢？在这种情况下的二进制搜索操作将失败。于是，他决定采用Jerry 的代码，搜索操作前对数据进行排序。于是，他会要求Subversion的从Jerry的分支到主干合并代码。
[tom@CentOS trunk]$ pwd /home/tom/project_repo/trunk [tom@CentOS trunk]$ svn merge ../branches/jerry_branch/ --- Merging r9 through r11 into '.': U array.c
合并后array.c的这个样子。
[tom@CentOS trunk]$ cat array.c
上面的命令将产生以下结果
#include <stdio.h> #define MAX 16 void bubble_sort(int *arr, int n) { int i, j, temp, flag = 1; for (i = 1; i < n && flag == 1; ++i) { flag = 0; for (j = 0; j < n - i; ++j) { if (arr[j] > arr[j + 1]) { flag = 1; temp = arr[j]; arr[j] = arr[j + 1]; arr[j + 1] = temp; } } } } int bin_search(int *arr, int n, int key) { int low, high, mid; low = 0; high = n - 1; mid = low + (high - low) / 2; while (low <= high) { if (arr[mid] == key) return mid; if (arr[mid] > key) high = mid - 1; else low = mid + 1; mid = low + (high - low) / 2; } return -1; } void accept_input(int *arr, int n) { int i; for (i = 0; i < n; ++i) scanf("%d", &arr[i]); } void display(int *arr, int n) { int i; for (i = 0; i < n; ++i) printf("|%d| ", arr[i]); printf(" "); } int main(void) { int i, n, ret, key, arr[MAX]; printf("Enter the total number of elements: "); scanf("%d", &n); /* Error handling for array overflow */ if (n > MAX) { fprintf(stderr, "Number of elements must be less than %d ", MAX); return 1; } printf("Enter the elements "); accept_input(arr, n); printf("Array has following elements "); display(arr, n); printf("Sorted data is "); bubble_sort(arr, n); display(arr, n); printf("Enter the element to be searched: "); scanf("%d", &key); ret = bin_search(arr, n, key); if (ret < 0) { fprintf(stderr, "%d element not present in array ", key); return 1; } printf("%d element found at location %d ", key, ret + 1); return 0; }
Tom 测试完成后，提交他的修改到版本库。
[tom@CentOS trunk]$ make array cc array.c -o array [tom@CentOS trunk]$ ./array Enter the total number of elements: 5 Enter the elements 10 -2 8 15 3 Array has following elements |10| |-2| |8| |15| |3| Sorted data is |-2| |3| |8| |10| |15| Enter the element to be searched: -2 -2 element found at location 1 [tom@CentOS trunk]$ svn commit -m "Merge changes from Jerry's code" Sending trunk Sending trunk/array.c Transmitting file data . Committed revision 12. [tom@CentOS trunk]$
