C語言中的指針和遞歸函數(shù)

RecursiveRecursion,aprocedureorsubroutine,implementedinaprogramminglanguage,whoseimplementationreferencesitself.Theimportanceoftherecursive1Sometimesrecursionhelpsyoutodesignsimplerandmorereadablecode.2Theadvantageisthatyoudonothavetopreservestateoneachiteration.3Itisespeciallyrelevantforrecursivedatastructures(liketrees)orrecursivealgorithms.UsingRecursiveinC:

Followingisthesourcecodeforafunctioncalledfactorial().Thisfunctiontakesoneparameter

numberandreturnsthenumberfactorial:

一下是factorial（）調(diào)用的函數(shù)的源代碼。該函數(shù)有一個參數(shù)number，并返回number的階乘。#include"stdio.h"http://functionreturningthedata'sfactorial.intfactorial(intnumber)//factorial(5)=5*4*3*2*1{ if(number==1)

return1; else

returnnumber*factorial(number-1);}intfactorial(intnumber);//FunctionDeclarationvoidmain(void){ inti;//localvariabledeclaration printf("Pleaseinputaninteger=>"); scanf("%d",&i); printf("Theinteger'sfactorial=>%d",factorial(i));

//callingthe'factorial'functiontogetaresult. getchar();getchar();}CPointers

Apointerisavariablewhosevalueistheaddressofanothervariable.Likeanyvariableorconstant,youmustdeclareapointerbeforeyoucanworkwithit.Thegeneralformofapointervariabledeclarationis:

type*var-name；

指針是一個變量，它的值是另一個變量的地址。像任何變量或常量，你必須聲明一個指針之前，你可以使用它。一個指針變量聲明的一般形式是：類型*VAR-名稱;TheimportanceofthepointerSomeCtasksareperformedmoreeasilywithpointers,andotherCtasks,suchasdynamicmemoryallocation,cannotbeperformedwithoutthem.UsingPointersinC:#include"stdafx.h"voidmain(){ inta，*ptr;

//variabledeclaration，pointervariable

ptr=&a;

//storeaddressofainpointervariable

printf("Pleaseinputaninteger=>");

scanf("%d",&(*ptr));//=scanf("%d",ptr);//printtheaddressstoredinippointervariable printf("theintegeraddress:%p\n",ptr);

//accessthevalueattheaddressavailableinpointer printf("a=%d",*ptr);}UsingPointersandRecursiveFunctioninC//calculate:sum=n+n-1+n-2+...+1//calculateUserinputthemaxnumber'saccumulate.#include"stdafx.h"#defineMAX(a,b)(a>b?a:b)//functionreturningthemaxbetweentwonumbersintassignment(int*p,int*q);//FunctionDeclarationintsum(intm);//FunctionDeclarationvoidmain(void){ intnumber1,number2;//localvariabledeclaration printf("Pleaseinputtwointegers=>"); printf("theMaxintegeraccumulatesum:%d",sum(assignment(&number1,&number2)));

//first:calling"assignment"functiontogetaMaxvalue.

//second:calling"sum"functiontogetresult.}intassignment(int*p,int*q)//functionreturningtheUserinputMaxdata.{ scanf("%d",&(*p));//&(*p)=p scanf("%d",&(*q));//&(*q)=q returnMAX(*p,*q);//callingMAXfunctionandret