上傳人：海***

認證信息

認證類型：機構(gòu)認證

認證主體：陽春市海霄網(wǎng)絡(luò)科技有限公司

IP屬地：廣東

統(tǒng)一社會信用代碼/組織機構(gòu)代碼

91441781MA52HUKW1K

IP屬地：廣東 上傳時間：2022-03-07 格式：DOC 頁數(shù)：17 大?。?7.50KB 積分：12 舉報 版權(quán)申訴

1、C+程序設(shè)計實例【例3.12】用下面公式求的近似值。/41-1/3+1/5-1/7+直到最后一項的絕對值小于10-7為止。根據(jù)給定的算法很容易編寫程序如下：. #include <iostream>. #include <iomanip>. #include <cmath>. using namespace std;. int main( ). . int s=1;. double n=1,t=1,pi=0;. while(fabs(t)>1e-7). . pi=

2、pi+t;. n=n+2;. s=-s;. t=s/n;. . pi=pi*4;. cout<<"pi="<<setiosflags(ios:fixed)<<setprecision(6)<<pi<<endl;. return 0;. 運行結(jié)果為pi=3.141592注意：不要把n定義為整型變量，否則在執(zhí)行“t=s/n;”時，得到t的值為0(原因是兩個整數(shù)相除)。【例3.13】求Fibonacci數(shù)列前40個數(shù)。這個數(shù)列有如下特點：第1、2個數(shù)為1、1。從第3個數(shù)開始，每個數(shù)是其前面兩個數(shù)之和。即：

3、60;   F1=1  (n=1)    F2=1  (n=2)    Fn=Fn-1+Fn-2(n3)這是一個有趣的古典數(shù)學(xué)問題：有一對兔子，從出生后第3個月起每個月都生一對兔子，小兔子長到第3個月后每個月又生一對兔子，假設(shè)所有兔子都不死，問每個月的兔子總數(shù)為多少？根據(jù)給出的每月兔子總數(shù)的關(guān)系，可編寫程序如下：1 / 17. #include <iostream>. #include <iomanip>. using namespace std;. int&#

4、160;main( ). . long f1,f2;. int i;. f1=f2=1;. for(i=1;i<=20;i+). . cout<<setw(12)<<f1<<setw(12)<<f2;. /設(shè)備輸出字段寬度為12,每次輸出兩個數(shù). if(i%2=0) cout<<endl;. /每輸出完4個數(shù)后換行,使每行輸出4個數(shù). f1=f1+f2;. /左邊的f1代表第3個數(shù),是第12個數(shù)之和. f2=f2+f1;. /左邊的f2代表第4個數(shù),是第23個數(shù)之和. . return&#

5、160;0;. 【例3.14】找出100200間的全部素數(shù)。編寫程序如下：. #include <iostream>. #include <cmath>. #include <iomanip>. using namespace std;. int main( ). . int m,k,i,n=0;. bool prime;/定義布爾變量prime. for(m=101;m<=200;m=m+2) /判別m是否為素數(shù),m由101變化到200,增量為2. .

6、 prime=true;/循環(huán)開始時設(shè)prime為真,即先認為m為素數(shù). k=int(sqrt(m); /用k代表根號m的整數(shù)部分. for(i=2;i<=k;i+) /此循環(huán)作用是將m被2根號m除,檢查是否能整除. if(m%i=0) /如果能整除,表示m不是素數(shù). . prime=false; /使prime變?yōu)榧? break; /終止執(zhí)行本循環(huán). . if (prime)/如果m為素數(shù). . cout<<setw(5)<<m; /輸出素數(shù)m,字段寬度為5. n=n+1; /n用

7、來累計輸出素數(shù)的個數(shù). . if(n%10=0) cout<<endl; /輸出10個數(shù)后換行. . cout<<endl;/最后執(zhí)行一次換行. return 0;. 【例3.15】譯密碼。為使電文保密，往往按一定規(guī)律將電文轉(zhuǎn)換成密碼，收報人再按約定的規(guī)律將其譯回原文。例如，可以按以下規(guī)律將電文變成密碼：將字母A變成字母E，a變成e，即變成其后的第4個字母，W變成A，X變成B，Y變成C，Z變成D。見圖3.20，字母按上述規(guī)律轉(zhuǎn)換，非字母字符不變，如"Wonderful!"轉(zhuǎn)換為"Asrhivjyp!"

8、。輸入一行字符，要求輸出其相應(yīng)的密碼。圖 3.20程序如下：. #include <iostream>. using namespace std;. int main( ). . char c;. while (c=getchar( )!='n'). . if(c>='a' && c<='z') | (c>='A' && c<

9、='Z'). . c=c+4;. if(c>'Z' && c<='Z'+4 | c>'z'). c=c-26;. . cout<<c;. . cout<<endl;. return 0;. 運行結(jié)果如下:I am going to Beijing!M eq ksmrk xs Fimnmrk!while語句中括號內(nèi)的表達式有3個作用：· 從鍵盤讀入一個字符，這是用getchar函數(shù)實現(xiàn)的；· 將讀入的字符賦

10、給字符變量c；· 判別這個字符是否為'n'(即換行符)。如果是換行符就執(zhí)行while語句中的復(fù)合語句(即花括號內(nèi)的語句)，對輸入的非換行符的字符進行轉(zhuǎn)換處理。按前面分析的思路對輸入的字符進行處理，有一點請讀者注意，內(nèi)嵌的if語句不能寫成：    if (c>'Z'| c>'z')  c=c-26;因為所有小寫字母都滿足“c>'Z'”條件，從而也執(zhí)行“c=c-26;”語句，這就會出錯。因此必須限制其范圍為“c>'Z' && c<=&

11、#39;Z'+4”，即原字母為'W'到'Z'，在此范圍以外的不是原大寫字母WZ，不應(yīng)按此規(guī)律轉(zhuǎn)換。請考慮：為什么對小寫字母不按此處理，即寫成c>'z' && c<='z'+4而只須寫成“c>'z'”即可。 計算拉格朗日插值的源程序#include <stdio.h>#include <conio.h>#include <stdlib.h>/#include <alloc.h>float Lagrange(float

12、*x,float *y,float xx,int n)int i,j;float *a,yy=0.0;a=(float *)malloc(n*sizeof(float);for(i=0;i<=n-1;i+)ai=yi;for(j=0;j<=n-1;j+)if(j!=i)ai*=(xx-xj)/(xi-xj);yy+=ai;free(a);return yy;void main()float x4=0.56160,0.56280,0.56401,0.56521;float y4=0.82741,0.82659,0.82577,0.82495;float xx=0.5635,yy;fl

13、oat Lagrange(float *,float *,float,int);yy=Lagrange(x,y,xx,4);/clrscr();printf("x=%f,y=%f/n",xx,yy);getch(); 編譯原理詞法分析器c+源程序#include<iostream.h>#include<fstream.h>#include<stdlib.h>#include<stdio.h>#include<string.h>#include<conio.h>#include<proce

14、ss.h> /*頭文件*/   void init();      char *DchangeB(char *buf);   int search(char *buf,int type,int command);      void intdeal(char *buffer);      void chardeal(char *buffer);   void errordeal(c

15、har error,int lineno);   void scanner();void init()      char *key="","auto","break","case","char","const","continue","default","do","double",    

16、;             "else","enum","extern","float","for","goto","if","int","long","register",         

17、;        "return","short","signed","sizeof","static","struct","switch","typedef",                 "u

18、nion","unsigned","void","volatile","while"     /*C語言所有關(guān)鍵字/    char *limit=" ","(",")","","","->",".","!","+","-",&quo

19、t;&","",                   "*","/","%","+","-","<<",">>","<","<=",">",

20、">=","=","!=","&&","|",                  "=","+=","-=","*=","/=",",","",""

21、,"","#","_","'"/*運算、限界符*/ fstream outfile;    int i,j; char *c; outfile.open("key.txt",iOS:out); for(i=0;i<32;i+)  outfile<<keyi<<endl; outfile.close(); outfile.open("Limi

22、t.txt",ios:out); for(j=0;j<38;j+)  outfile<<limitj<<endl; c="" outfile<<c; outfile.close(); outfile.open("bsf.txt",ios:out); outfile.close(); outfile.open("cs.txt",ios:out); outfile.close();

23、0;outfile.open("output.txt",ios:out); outfile.close();char *DchangeB(char *buf)           int temp20; char *binary; int value=0,i=0,j; for(i=0;bufi!='/0'i+)  value=value*10+(bufi-48);   &

24、#160;   /*將字符轉(zhuǎn)化為十進制數(shù)*/    if(value=0)      binary=new char2;  binary0='0'  binary1='/0'  return(binary);  i=0; while(value!=0)      tempi+=value%2;  value

25、/=2;  tempi='/0' binary=new chari+1; for(j=0;j<=i-1;j+)       binaryj=(char)(tempi-j-1+48);    binaryi='/0'    return(binary);  /*十進制轉(zhuǎn)化為二進制*/int search(char *buf,int type,int command) int number=0

26、;    fstream outfile;    char ch;    char temp30;    int i=0;    switch(type)     case 1: outfile.open("key.txt",ios:in);break;    case 2: outfile.open("bsf.txt",ios:in);

27、break;    case 3: outfile.open("cs.txt",ios:in);break;    case 4: outfile.open("limit.txt",ios:in);break;     outfile.get(ch); while(ch!=EOF)     while(ch!='/n')      

28、              tempi+=ch;            outfile.get(ch);                tempi='/0'     

29、;   i=0;        number+;        if(strcmp(temp,buf)=0)                outfile.close();   return number;     &#

30、160;  /*若找到，返回在相應(yīng)表中的序號*/                else          outfile.get(ch);                  &#

31、160;         /結(jié)束外層while循環(huán)     if(command=1)              outfile.close( );    return 0;             

32、   /*找不到，當(dāng)只需查表，返回0，否則還需造表*/       switch(type)     case 1: outfile.open("key.txt",ios:in);break;    case 2: outfile.open("bsf.txt",ios:in);break;    case 3: outfile.open("cs.txt",i

33、os:in);break;    case 4: outfile.open("limit.txt",ios:in);break;    outfile<<buf;outfile.close(); return number+1;void intdeal(char *buffer)  fstream outfile;    int result;    result=search(buffer,1,1);  

34、;         /*先查關(guān)鍵字表*/    outfile.open("output.txt",ios:app);    if(result!=0)       outfile<<buffer<<result<<endl;  /*若找到，寫入輸出文件*/    else  

35、60;         result=search(buffer,2,2);       /*若找不到，則非關(guān)鍵字，查標(biāo)識符表，還找不到則造入標(biāo)識符表*/        outfile<<buffer<<result<<endl;            

36、                         /*寫入輸出文件*/    outfile.close();void chardeal(char *buffer)    fstream outfile;    int result;   

37、 result=search(buffer,1,1);           /*先查關(guān)鍵字表*/ outfile.open("output.txt",ios:app);    if(result!=0)       outfile<<buffer<<result<<endl;   /*若找到，寫入輸出文件*/ &

38、#160;  else            result=search(buffer,2,2);       /*若找不到，則非關(guān)鍵字，查標(biāo)識符表，還找不到則造入標(biāo)識符表*/       outfile<<buffer<<result<<endl;        

39、;                             /*寫入輸出文件*/    outfile.close();void errordeal(char error,int lineno)  cout<<"/nerror: "<<

40、error<<" ,line"<<lineno;void scanner()   fstream  infile,outfile;    char filename20;    char ch; int err=0;    int i=0,line=1;    int count,result,errorno=0; char array30;    ch

41、ar *word; printf("/n please input the file scanner name:");    scanf("%s",filename);     err=1;    infile.open(filename,ios:nocreate|ios:in);    while(! infile)         &

42、#160;  cout<<"cannot open file"<<endl;        printf("please input  the file  name again:/n");  scanf("%s",filename);        infile.open(filename,ios:nocreate|ios:

43、in);        err+;  if(err=3)  cout<<"SORROY YOU CAN'T VUEW THE PRGARME/n"        cout<<"TANKE YOU VIEW"<<endl;    exit(0);     &

44、#160;  infile.get(ch);    while(ch!=EOF)                     /*按字符依次掃描源程序，直至結(jié)束*/        i=0;        if(ch>='

45、A')&&(ch<='Z')|(ch>='a')&&(ch<='z')|(ch='_')                   /*以字母開頭*/            while(ch>=&#

46、39;A')&&(ch<='Z')|(ch>='a')&&(ch<='z')|(ch='_')|(ch>='0')&&(ch<='9')                        &#

47、160;   arrayi+=ch;                infile.get(ch);                        word=new chari+1;  

48、60;memcpy(word,array,i);   wordi='/0'            intdeal(word);            if(ch!=EOF)    infile.seekg(-1,ios:cur);     &#

49、160;          else if(ch>='0'&&ch<='9')                  /*以數(shù)字開頭*/            while(ch>='

50、;0'&&ch<='9')                            arrayi+=ch;                infi

51、le.get(ch);                        word=new chari+1;   memcpy(word,array,i);   wordi='/0'          

52、60; intdeal(word);            if(ch!=EOF)    infile.seekg(-1,ios:cur);                else if(ch=' ')|(ch='/t')    

53、0;         /*消除空格符和水平制表符*/  else if(ch='/n')   line+;           /*消除回車并記錄行數(shù)*/  else if(ch='/')           

54、0;             /*消除注釋*/   infile.get(ch);   if(ch='=')                 /*判斷是否為/=符號*/    outfile.open(&

55、quot;output.txt",ios:noreplace|ios:app);    outfile<<"/=/t/t/t4/t/t/t32/n"                outfile.close();      else if(ch!='*')   

56、                       /*若為除號，寫入輸出文件*/                outfile.open("output.txt",ios:noreplace|ios:app); &

57、#160;  outfile<<"/t/t/t4/t/t/t13/n"                outfile.close();    outfile.seekg(-1,ios:cur);      else if(ch='*')    

58、;             /*若為注釋的開始，消除包含在里面的所有字符*/    count=0;   infile.get(ch);    while(count!=2)                 &

59、#160;        /*當(dāng)掃描到*且緊接著下一個字符為/才是注釋的結(jié)束*/     count=0;     while(ch!='*')      infile.get(ch);     count+;      infile.get(ch);&

60、#160;    if(ch='/')      count+;     else      infile.get(ch);           else if(ch='"')     &

61、#160;             /*消除包含在雙引號中的字符串常量*/   outfile.open("output.txt",ios:noreplace|ios:app);      outfile<<ch<<"/t/t/t4/t/t/t37/n"   outfile.close(); &

62、#160; while(ch!='"')   infile.get(ch);            infile<<ch<<"/t/t/t4/t/t/t37/n"   infile.close();    else         

63、;        /*首字符為其它字符,即運算限界符或非法字符*/            array0=ch;            infile.get(ch);       /*再讀入下一個字符，判斷是否為雙字符運算、限界符*/ 

64、60;          if(ch!=EOF)                       /*若該字符非文件結(jié)束符*/               

65、; array1=ch;    word=new char3;    memcpy(word,array,2);    word2='/0'                result=search(word,4,1);      /*先檢索是否為雙字符運算、限界

66、符*/    if(result=0)                               /*若不是*/            &

67、#160;       word=new char2;     memcpy(word,array,1);     word1='/0'     result=search(word,4,1);      /*檢索是否為單字符運算、限界符*/     if(result=0

68、)                                               /*若還不是，則為非法字符*/  

69、    errordeal(array0,line);      errorno+;      infile.seekg(-1,ios:cur);                         &#

70、160;              else          /*若為單字符運算、限界符，寫入輸出文件并將掃描文件指針回退一個字符*/      outfile.open("output.txt",ios:noreplace|ios:app);      outfile<<word<<"/t/t/t4/t/t/t"<<result<<"/t"<<endl;      outfile.close();