questions about recursion(C language)

2007-04-24 6:25 pm

我想問係一個recursive function入面
我放左個"return"入去
咁係唔係當個function行到return就會做完成個function,唔理之前recursion左幾多次?

e.g
我寫左一段code係咁:
member* search (member* find, char* name){
if(find){
if(strcmp(name,find->name)==0)
return find;
else{
search(find->left_child,name);
search(find->right_brother,name);
}
}
}

我係想用黎係一棵ｆａｍｉｌｙ　ｔｒｅｅ入面
搵番一個岩名個ｐａｒｅｎｔ
咁樣我呢個ｆｕｎｃｔｉｏｎ係唔係一搵到岩名就會ｒｅｔｕｒｎ個岩名既ｍｅｍｂｅｒ既ｐｒｏｉｎｔｅｒ，　而唔繼續搵落去？
thx

更新1:

咁我係唔係應該要加一句ｍｅｍｂｅｒ　＊ｔｍｐ；ｔｍｐ　＝　（ｍｅｍｂｅｒ＊）ｍａｌｌｏｃ（ｓｉｚｅｏｆ（ｍｅｍｂｅｒ））；一話唔要ｍａｌｌｏｃ？

回答 (1)

用戶97753

2007-04-24 9:59 pm

✔ 最佳答案

Yes, you should return the result when you can find the right name, but in your program, you have not return the result from recursion, you should have like:

member* search (member* find, char* name){
....
else {
member* tmp = search(find->left_child,name);
if (tmp != NULL) tmp = search(find->right_brother,name);
return tmp;
}
.....

Yet the function will stop when return statement is reached, but it will return to the upper level of recursion function and continue the upper level.
e.g.
search(a, b) {
....
search(c,d);
....
}
when search(c,d) ends, the control will pass to search(a,b) and continue.

P.S.: C cannot stop the whole recursion at once, but C++ or JAVA can by applying try-catch clause.

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