c語言課后答案-電子科技大學(xué)出版社

語言程序設(shè)計(jì)教程答案第一章C語言歸納一、簡答題1．（1）語言簡潔、緊湊，使用方便、靈便；（2）運(yùn)算符豐富；（3）擁有豐富的數(shù)據(jù)種類；（4）擁有結(jié)構(gòu)化的控制語句；（5）語法限制不太嚴(yán)格，程序設(shè)計(jì)自由度大；（6）C語言贊同直接接見物理地址，能進(jìn)行位（bit）操作，能實(shí)現(xiàn)匯編語言的大部分功能，能夠直接接見硬件；（7）生成目標(biāo)代碼質(zhì)量高，程序執(zhí)行效率高；（8）用C語言寫的程序可移植性好，基本上不作更正就能用于各種型號的計(jì)算機(jī)和各種操作系統(tǒng)。2．序次結(jié)構(gòu)，分支結(jié)構(gòu)，循環(huán)結(jié)構(gòu)3．所謂算法就是為解決一個(gè)問題而采用的方法和步驟。算法的特點(diǎn)：有窮性、確定性、輸入、輸出、可行性。表示算法的方式：（1）用自然語言表示；（2）用流程圖表示；（3）用N—S流程圖表示；（4）用偽代碼表示；（5）用計(jì)算機(jī)語言表示。二、算法1．瓶子A里盛有醋瓶子B里盛有醬油有一個(gè)空瓶C將A中的醋倒入C將B中的醬油倒入A將C中的醋倒入B2．輸入一個(gè)數(shù)放在a中max=a以下步驟重復(fù)9次：輸入一個(gè)數(shù)放在a中若是a>max，max=a打印max的值3．若是a<btemp=aa=bb=temp若是c>atemp=aa=cc=temp否則若是c>btemp=bb=cc=temp打印a,b,c的值4．i=1sum=0以下程序循環(huán)100遍：sum=sum+ii=i+1打印sum的值5．若是（n除以3的余數(shù)為0并且n除以5的余數(shù)為0）n能夠同時(shí)被3和5整除否則n不能夠夠同時(shí)被3和5整除6．i=101以下語句循環(huán)50遍：j=2flag=1當(dāng)j<（i除以2的整數(shù)部分）時(shí)循環(huán)以下語句：若是i除以j的余數(shù)為零flag=0退出該循環(huán)若是flag==1打印i的值i=i+27．若是m<ntemp=mm=nn=tempi=n做以下循環(huán)，直到m,n能夠被i整除：若是m能夠被i整除并且n能夠被i整除i即是m和n的最大合約數(shù)跳出循環(huán)否則i=i-1打印i的值8．data=b*b—4*a*c若是data＞0否則若是data=0x1=x2=—b/2否則無實(shí)數(shù)解三、編程題1．main（）{printf(“##############################\n”）；printf(“Howdoyoudo？\n”）；printf(“##############################\n”)；}2．main（）{inta,b,c;scanf(“%d%d%d”,&a,&b,&c);printf(“sum=%d”,a+b+c);}第二章數(shù)據(jù)種類與表達(dá)式一、單項(xiàng)選擇題1.B2.C3.A4.A5.D6.B二、寫出以下程序的運(yùn)行結(jié)果1.aabbccabcAN2.ab97989,11,9,10a=2,b=3,c=2s1=s2=3三、編程題main(){charc1='c',c2='h',c3='i',c4='n',c5='a';c1=c1+4;c2=c2+4;c3=c3+4;c4=c4+4;c5=c5+4;printf("%c%c%c%c%c\n",c1,c2,c3,c4,c5);}第三章序次程序設(shè)計(jì)選擇題1）B2）D3）D4）A5）A6）B7）B8）A9）D10）C11）D12）A填空題1）b2）2613）2521374）abc5）,4,c=36）3編程題#definePImain(){floath,r,l,sv,sz;printf(“請輸入圓的半徑r，圓柱高h(yuǎn)：\n”);scanf(“%f,%f”,&r,&h);l=2*PI*r;s=PI*r*r;sv=*PI*r*r*r;sz=PI*r*r*h;printf(“圓周長為：l=%,圓面積為：s=%\n”,l,s);printf(“求體積為：sv=%,圓柱體積為：sz=%\n”,sv,sz);}2、main(){floatc,f;printf(“請輸入一個(gè)華氏溫度：\n”);scanf(“%f”,&f);c=*(f-32);printf(“攝氏溫度為：%\n”,c);}第四章循環(huán)程序設(shè)計(jì)一、選擇題二、填空題１．585858２．0３．18４．8921５．２０，０６．６７．１，３，２8．Year%400==0year%100!=0count++三、編程題1.main(){longa;scanf(“%ld”,&a);if(a>=10000&&a<=99999)printf(“這是個(gè)五位數(shù)”)；elseif(a>=1000&&a<=9999)printf(“這是個(gè)四位數(shù)”)；elseif(a>=100&&a<=999)printf(“這是個(gè)三位數(shù)”)；elseif(a>=10&&a<=99)printf(“這是個(gè)二位數(shù)”)；elseif(a>=0&&a<=9)printf(“這是個(gè)一位數(shù)”)；elseprintf(“輸入錯(cuò)誤”)；}3.main(){inta;intg,s,b;B2.A3.C4.C5.D6.BB二、寫出以下程序的運(yùn)行結(jié)果1．S=3682．*************************3．S1=18S2=104．!margorP5．?dāng)?shù)字0的出現(xiàn)次數(shù)是：3數(shù)字1的出現(xiàn)次數(shù)是：2數(shù)字2的出現(xiàn)次數(shù)是：2數(shù)字3的出現(xiàn)次數(shù)是：2數(shù)字4的出現(xiàn)次數(shù)是：0數(shù)字5的出現(xiàn)次數(shù)是：1數(shù)字6的出現(xiàn)次數(shù)是：1數(shù)字7的出現(xiàn)次數(shù)是：1數(shù)字8的出現(xiàn)次數(shù)是：1數(shù)字9的出現(xiàn)次數(shù)是：1三、編程題1．#include""main(){inta[11];inti,j,t;printf("input10number:\n");for(i=1;i<11;i++)scanf("%d",&a[i]);printf("\n");for(i=1;i<=9;i++)for(j=1;j<=10-i;j++)if(a[j]<a[j+1]){t=a[j];a[j]=a[j+1];a[j+1]=t;}printf("thesortednumberis:\n");for(i=1;i<11;i++)printf("%4d",a[i]);}2．#include""main(){inta[11],i,b;printf("imput10sortednumber:\n");for(i=0;i<10;i++)scanf("%d",&a[i]);printf("inputaninteger:\n");scanf("%d",&b);for(i=9;i>=0&&a[i]>b;i--)a[i+1]=a[i];a[i+1]=b;printf("sortednumbers:\n");for(i=0;i<11;i++)printf("%5d",a[i]);}3．#include""main(){inta[5],i,j,t;printf("input5integer:\n");for(i=0;i<5;i++)scanf("%d",&a[i]);for(i=0,j=4;i<j;i++,j--){t=a[i];a[i]=a[j];a[j]=t;}for(i=0;i<5;i++)

/*輸入5個(gè)整數(shù)*//*逆序存放*//*逆序存放后重新輸出*/printf("%5d",a[i]);}4．#include""main(){inti,j,a[10][10]={{1},{1,1}};for(i=2;i<10;i++)組每個(gè)元素賦值*/{a[i][0]=1;for(j=1;j<=i;j++)a[i][j]=a[i-1][j-1]+a[i-1][j];}for(i=0;i<10;i++)數(shù)組*/{for(j=0;j<=i;j++)printf("%-5d",a[i][j]);printf("\n");}}5．#include""main(){inta[3][4],i,j,max,row,col;printf("input3*4matrix:\n");for(i=0;i<3;i++)for(j=0;j<4;j++)

/*給二維數(shù)/*輸出二維/*輸入3*4矩陣*/scanf("%d",&a[i][j]);max=a[0][0];row=0;col=0;for(i=0;i<3;i++)/*搜尋矩陣中的最大值及其行列號*/for(j=0;j<4;j++)if(max<a[i][j]){max=a[i][j];row=i,col=j;}printf("\n數(shù)組中最大的數(shù)是%d,其行號是%d,列號是%d\n",max,row,col);}6．#defineN3#defineM4#include""main(){inta[N][M],i,j,k,max,row,col;printf("input%d*%dmatrix:\n",N,M);for(i=0;i<N;i++)for(j=0;j<M;j++)scanf("%d",&a[i][j]);for(i=0;i<N;i++){max=a[i][0];row=i;for(j=1;j<M;j++)

col=0;

/*

/*輸入二維矩陣/*求鞍點(diǎn)*/求矩陣中每一行的最大

*/值及其所行列號

*/if(max<a[i][j]){max=a[i][j];

col=j;}for(k=0;k<N;k++)

/*

判斷每一行的最大值在其所在列可否最大*/if(a[k][col]<max)break;if(k==N){printf("the

/*獲取鞍點(diǎn)*/pointis%d,row=%d,col=%d\n",max,row,col);break;}}if(i==N)printf("nopoint\n");}7．#include""main(){intnum=0,word=0;/*word=0表示未出現(xiàn)單詞

/*沒有鞍點(diǎn)*/,如出現(xiàn)單詞就置word為用來統(tǒng)計(jì)單詞個(gè)數(shù)*/charc;printf("pleaseinputastring:\n");while((c=getchar())!='\n')if(c=='')word=0;elseif(word==0){word=1;num++;}printf("Thereare%dwordsintheline\n",num);}8．#include""main(){inti,j,uppn,lown,dign,span,othn;/*uppn,lown,dign,span,othn分別存放英文大寫字母、小寫字母、數(shù)字、空格和其他字符的個(gè)數(shù)*/chartext[3][80];uppn=lown=dign=span=othn=0;for(i=0;i<3;i++){gets(text[i]);for(j=0;j<80&&text[i][j]!='\0';j++){if(text[i][j]>='A'&&text[i][j]<='Z')uppn++;elseif(text[i][j]>='a'&&text[i][j]<='z')lown++;elseif(text[i][j]>='0'&&text[i][j]<='9')dign++;elseif(text[i][j]=='')span++;elseothn++;}}for(i=0;i<3;i++)printf("%s\n",text[i]);printf("uppn=%d\n",uppn);printf("lown=%d\n",lown);printf("dign=%d\n",dign);printf("span=%d\n",span);printf("othn=%d\n",othn);}9．#include""main(){inti,j;charstr1[20],str2[20];printf("inputtwostrings:\n");gets(str1);gets(str2);j=strlen(str1);

/*

求字符串

1的長度*/for(i=0;str2[i]!='\0';i++,j++)

/*字符串合并

*/str1[j]=str2[i];str1[j]='\0';

/*加上字符串結(jié)束標(biāo)志*/puts(str1);}10．#include""main(){inti,n;charstr1[20],str2[20];printf("inputtwostrings:(nomorethan20characters)\n");gets(str1);gets(str2);n=strlen(str1)<strlen(str2)?strlen(str1):strlen(str2);/*n中存放較短字符串的長度*/for(i=0;i<n&&str1[i]==str2[i];i++);printf("%d\n",str1[i]-str2[i]);}第六章函數(shù)與編譯預(yù)辦理一、單項(xiàng)選擇題10.A二、寫出以下程序的運(yùn)行結(jié)果1．92．4,B8,B3．4．a(chǎn)=6,b=55．48三、編程題1．main(){intprime(intn);intn;printf("inputn(n>0):\n");scanf("%d",&n);if(prime(n))printf("%disasushu\n",n);elseprintf("%disnotasushu\n",n);}intprime(intn){intflag=1,i;for(i=2;i<=n/2&&flag==1;i++)if(n%i==0)flag=0;return(flag);}2.#defineN3convert(intarray[3][3]){inti,j,t;for(i=0;i<N-1;i++)for(j=i+1;j<N;j++){t=array[i][j];array[i][j]=array[j][i];array[j][i]=t;}}main(){inti,j;inta[N][N];printf("inputa:\n");for(i=0;i<N;i++)for(j=0;j<N;j++)scanf("%d",&a[i][j]);printf("Arraya:\n");for(i=0;i<N;i++){for(j=0;j<N;j++)printf("%5d",a[i][j]);printf("\n");}convert(a);printf("adezhuanzhiis:\n");for(i=0;i<N;i++){for(j=0;j<N;j++)printf("%5d",a[i][j]);printf("\n");}}#include<>#include<>main(){charstr[100];printf("inputastring:\n");gets(str);inverse(str);printf("thereversedstringis:%s\n",str);}inverse(charstr[]){chart;inti,j;for(i=0,j=strlen(str)-1;i<j;i++,j--){t=str[i];str[i]=str[j];str[j]=t;}}4.#include<>concat(charstr1[],charstr2[]){inti=0,j;while(str1[i]!='\0')i++;for(j=0;str2[j]!='\0';i++,j++)str1[i]=str2[j];str1[i]='\0';}main(){charstr1[100],str2[100];gets(str1);gets(str2);concat(str1,str2);puts(str1);}main(){charstr[80];printf("inputastring(4geshuzizifu):\n");scanf("%s",str);insert(str);printf("resultis:\n%s\n",str);}insert(charstr[]){inti;for(i=strlen(str);i>0;i--){str[2*i]=str[i];str[2*i-1]='';}}6.#include""inti,ndight,nwhite,nletter,nother;count(charstr[]){ndight=nwhite=nletter=nother=0;for(i=0;str[i]!='\0';i++)if(str[i]>='0'&&str[i]<='9')ndight++;elseif((str[i]>='A'&&str[i]<='Z')||(str[i]>='a'&&str[i]<='z'))nletter++;elseif(str[i]=='')nwhite++;elsenother++;}main(){chartext[80];printf("inputastring:\n");gets(text);count(text);printf("ndight=%d,nletter=%d,nwhite=%d,nother=%d\n",ndight,nletter,nwhite,nother);}7.#defineN10#include<>sort(charstr[]){inti,j;chart;for(i=1;i<N;i++)for(j=0;j<N-i;j++)if(str[j]>str[j+1]){t=str[j];str[j]=str[j+1];str[j+1]=t;}}main(){charstr[N];inti;printf("Input10gezifu:\n");gets(str);sort(str);printf("Thesortedresult:\n");for(i=0;i<N;i++)printf("%c",str[i]);}8.這題較復(fù)雜#include<>#include<>#defineN10voidinput_e(intnum[],charname[N][8]){inti;for(i=0;i<N;i++){printf("inputgonghao:");scanf("%d",&num[i]);printf("inputname:");getchar();gets(name[i]);}for(i=0;i<N;i++)printf("%5d%10s\n",num[i],name[i]);}voidsort(intnum[],charname[N][8]){inti,j,min,temp1;chartemp2[8];for(i=0;i<N-1;i++){min=i;for(j=i+1;j<N;j++)if(num[j]<num[min])min=j;temp1=num[i];

/*

選擇法排序

*/strcpy(temp2,name[i]);num[i]=num[min];strcpy(name[i],name[min]);num[min]=temp1;strcpy(name[min],temp2);}printf("thesortedresult:\n");for(i=0;i<N;i++)printf("%5d%10s\n",num[i],name[i]);}voidsearch(intn,intnum[],charname[N][8])

/*

折半查找法*/{inttop,bott,mid,find;find=0;top=0;bott=N-1;if((n<num[0])||(n>num[N-1]))find=-1;while((find==0)&&(top<=bott)){mid=(bott+top)/2;if(n==num[mid]){find=1;printf("%dnameis:%s\n",n,name[mid]);}elseif(n<num[mid])bott=mid-1;elsetop=mid+1;}if((find==-1)||(find==0))printf("%disnotfound.\n",n);}main(){intnum[N],number,c,flag;charname[N][8];input_e(num,name);sort(num,name);for(flag=1;flag;){printf("pleaseinputchazhaodegonghao:");/*輸入查找的工號*/scanf("%d",&number);search(number,num,name);printf("continueY/N?");/*可否連續(xù)查找*/getchar();c=getchar();if(c=='N'||c=='n')flag=0;}}#include""#defineMAX10main(){charstr[MAX];charc;inti;i=0;printf("inputnumber(16jinzhi):");/*輸入一個(gè)十六進(jìn)制的數(shù)*/while((c=getchar())!='\n'&&i<MAX){str[i]=c;i++;}str[i]='\0';printf("resultis:%d\n",htod(str));}inthtod(chars[]){inti,n;n=0;for(i=0;s[i]!='\0';i++){if(s[i]>='0'&&s[i]<='9')n=n*16+s[i]-'0';if(s[i]>='a'&&s[i]<='f')n=n*16+s[i]-'a'+10;if(s[i]>='A'&&s[i]<='F')n=n*16+s[i]-'A'+10;}return(n);}#defineSWAP(a,b)t=a;a=b;b=tmain(){inta,b,t;printf("inputa,b:");scanf("%d,%d",&a,&b);SWAP(a,b);printf("result:a=%d,b=%d\n",a,b);}11.#defineSURPLUS(a,b)((a)%(b))main(){inta,b;printf("inputa,b:");scanf("%d,%d",&a,&b);printf("resultis:%d\n",SURPLUS(a,b));}main(){inta,b,c;printf("inputa,b,c:");scanf("%d,%d,%d",&a,&b,&c);printf("max=%d\n",max(a,b,c));}intmax(intx,inty,intz){intt;t=(x>y?x:y);return(t>z?t:z);}#defineMAX(x,y)((x)>(y)?(x):(y))main(){inta,b,c;printf("inputa,b,c:");scanf("%d,%d,%d",&a,&b,&c);printf("max=%d\n",MAX(MAX(a,b),c));}13.#include""#defineCHANGE1#defineMAX80main(){charstr[MAX];inti;printf("inputastring:\n");gets(str);#if(CHANGE){for(i=0;str[i]!='\0';i++)if(str[i]>='a'&&str[i]<'z'||str[i]>='A'&&str[i]<'Z')str[i]=str[i]+1;elseif(str[i]=='z'||str[i]=='Z')str[i]=str[i]-25;}#endifprintf("%s\n",str);}第七章指針一、選擇題1）A2）D3）D4）C5）B6）B7）B8）C9）B10）C11）A12）A13）A14）C15）B16）A17）C18）B19）D20）B二、閱讀下面程序，寫出程序運(yùn)行結(jié)果1）abcdeedcba2）193）（TurboC中是11,97,11）（VisualC是9，97，11）4）365）6385三、編程題1、main(){inta[10],i,temp,*p=a;printf("Pleaseinputarraya:\n");for(i=0;i<10;i++)scanf("%d",&a[i]);printf("arraya:\n");for(i=0;i<10;i++)printf("%4d",a[i]);for(i=0;i<5;i++){temp=p[i];p[i]=p[10-i-1];p[10-i-1]=temp;}printf("\nNowarraya:\n");for(i=0;i<10;i++)printf("%4d",a[i]);}2、main(){inta[3][3],*p,i,j;printf("pleaseinputmatrix:\n");for(i=0;i<3;i++)for(j=0;j<3;j++)scanf("%d",&a[i][j]);p=&a[0][0];move(p);printf("\nNowmatrix:\n");for(i=0;i<3;i++){for(j=0;j<3;j++)printf("%4d",a[i][j]);printf("\n");}}move(int*q){inti,j,t;for(i=0;i<3;i++)for(j=i;j<3;j++){t=*(q+3*i+j);*(q+3*i+j)=*(q+3*j+i);*(q+3*j+i)=t;}}3、#include<>#include<>#include<>#include<>main(){intbinary();voidinsert();char*temp,*ptr1[6]={"BASIC","DATA","PASCAL","SQL","USE"};inti;ptr1[5]=malloc(20);printf("\n");printf("originalstring:\n");for(i=0;i<5;i++)printf("%s\n",ptr1[i]);printf("inputsearchstring:\n");temp=malloc(20);gets(temp);i=binary(ptr1,temp,5);printf("i=%d\n",i);insert(ptr1,temp,5,i);printf("outputstrings:\n");for(i=0;i<6;i++)printf("%s\n",ptr1[i]);}intbinary(char*ptr[],char*str,intn){inthig,low,mid;low=0;hig=n-1;if(strcmp(str,ptr[0])<0)return(0);if(strcmp(str,ptr[hig])>0)return(n);while(low<=hig){mid=(low+hig)/2;if(strcmp(str,ptr[mid])<0)hig=mid-1;elseif(strcmp(str,ptr[mid])>0)low=mid+1;elsereturn(mid);}return(low);}voidinsert(char*ptr[],char*str,intn,inti){intj;for(j=n;j>i;j--)strcpy(ptr[j],ptr[j-1]);strcpy(ptr[i],str);}4、main(){inti;char*p[6],str[6][20];for(i=0;i<6;i++)p[i]=str[i];printf("Input6strings:\n");for(i=0;i<6;i++)scanf("%s",p[i]);sort(p);printf("Nowthestrings:\n");for(i=0;i<6;i++)printf("%s\n",p[i]);}sort(char*q[]){inti,j;char*t;for(i=0;i<5;i++)for(j=0;j<5-i;j++)if(strcmp(*(q+j),*(q+j+1))>0){t=*(q+j);*(q+j)=*(q+j+1);*(q+j+1)=t;}}5、main(){intm;charstr1[20],str2[20],*p1,*p2;printf("pleaseinputtwostrings:\n");scanf("%s",str1);scanf("%s",str2);p1=str1;p2=str2;m=stringcmp(p1,p2);printf("resultis%d:\n",m);}stringcmp(char*p1,char*p2){inti=0;while(*(p1+i)==*(p2+i))if(*(p1+(i++))=='\0')return(0);return((*p1+i)-*(p2+i));}6、main(){charstr1[30],str2[30],str3[100];inti=0,j=0,k=0;printf("pleaseinputtwostrings:\n");scanf("%s",str1);scanf("%s",str2);while(str1[i]!='\0'&&str2[j]!='\0'){str3[k++]=str1[i++];str3[k++]=str2[j++];}while(str1[i]!='\0')str3[k++]=str1[i++];while(str2[j]!='\0')str3[k++]=str2[j++];str3[k]='\0';printf("\n%s\n",str3);}第八章結(jié)構(gòu)體一、選擇題1、C2、B3、C4、D5、B6、A7、D8、C9、C10、B二、填空題1、342、03、514、10，x5、364041三、編程題1、structcomplex{floatx;/*實(shí)部*/floaty;/*虛部*/}main(){structcomplexc1={5,3},c2={2,6};floatt1,t2;t1=*-*;t2=*+*;printf(“Thetwocomplexsproductis:”);printf(“%.2f%+.n2f”i,t1,t2);}2.structstudent{charname[10];/*姓名*/intnumber;/*學(xué)號*/floatx;/*成績*/floaty;/*成績*/}main(){structstudents[45];inti;voidmax();voidaverage();voidsort();for(i=0;i<45;i++)scanf(“%s%d%f%d”,s[i].name,&s[i].number,&s[i].x,&s[i].y);/*輸入學(xué)生的姓名、學(xué)號、兩門課程成績*/max(s,45);average(s,45);sort(s,45);}voidmax(structstudent*a,intn){floattemp;charna[10];inti,num;temp=a[0].x+a[0].y;for(i=1;i<n;i++)if(temp<a[i].x+a[i].y)/*求總分最高的學(xué)生姓名、學(xué)號*/{temp=a[i].x+a[i].y;strcmp(na,a[i].name);num=a[i].number;}printf(“%s,%d”,na,num);}voidaverage(structstudent*b,intn){floataver1,aver2,s1,s2;inti;s1=s2=0;for(i=0;i<45;i++)/*求每門課程的總成績*/{s1+=b[i].x;s2+=b[i].y;}aver1=s1/45;aver2=s2/45;for(i=0;i<45;i++)if(b[i].x<aver1&&b[i].y<aver2)/*輸出兩門課程都低于平均成績的學(xué)生*/printf(“%s,%dn”,b[i].name,b[i].number);}voidsort(structstudent*c,intn){本

floatt;inti,j;structstudenttemp;for(i=0;i<n-1;i++)P89頁*/{k=i;for(j=i+1;j<n;j++)if(c[k].x<c[j].x)k=j;if(k!=i){temp=c[i];c[i]=c[k];c[k]=temp;}

/*

改進(jìn)的選擇法排序可參照課for(i=0;i<n;i++)printf(“%s,%n.”2f,c[i].n,c[i].x);}3.typedefstructLjian{intpname;intwnum;structLjian*next;}Part;/*用戶自定義零件結(jié)構(gòu)體種類*/#include“”main(){intn=1;Part*head,*p1,*p2;head=NULL;p1=(Part*)malloc(sizeof(structLjian));/*創(chuàng)辦第一個(gè)結(jié)點(diǎn)*/scanf(“%d%d”,&p1->pname,&p1->wnum);p1->next=NULL;while(n<=10)/*將結(jié)點(diǎn)加入鏈表*/{if(n==1)head=p1;

/*是第一個(gè)結(jié)點(diǎn)，作表頭

*/