凯撒加密算法c语言实现

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1、凯撒加密算法C语言实现#include#includecharencrypt(charch,intn)/*加密函数，把字符向右循环移位n*/{while(ch>='A'&&ch<='Z'){  return('A'+(ch-'A'+n)%26);}while(ch>='a'&&ch<='z'){  return('a'+(ch-'a'+n)%26);}returnch;}voidmenu()/*菜单，1.加密，2.解密，3.暴力破解，密码只能是数字*/{clrscr();printf("=========================

2、======================================================");printf("1.Encryptthefile");printf("2.Decryptthefile");printf("3.Forcedecryptfile");printf("4.Quit");printf("===============================================================================");printf("Pleaseselectaitem:");ret

3、urn;}voidlogo()/*显示版权信息*/{printf("ZhensoftEncryption[Version:1.0.0]");printf("Copyright(C)2004ZhensoftCorp.");printf("http://www.zhensoft.com");return;}main(){inti,n;charch0,ch1;FILE*in,*out;charinfile[20],outfile[20];textbackground(BLACK);textcolor(LIGHTGREEN);clrscr();logo();sle

4、ep(3);/*等待3秒*/menu();ch0=getch();while(ch0!='4'){  if(ch0=='1')  {  clrscr();  printf("Pleaseinputtheinfile:");  scanf("%s",infile);/*输入需要加密的文件名*/  if((in=fopen(infile,"r"))==NULL)  {    printf("Cannotopentheinfile!");    printf("Pressanykeytoexit!");    getch();    exit(0);  }  print

5、f("Pleaseinputthekey:");  scanf("%d",&n);/*输入加密密码*/  printf("Pleaseinputtheoutfile:");  scanf("%s",outfile);/*输入加密后文件的文件名*/  if((out=fopen(outfile,"w"))==NULL)  {    printf("Cannotopentheoutfile!");    printf("Pressanykeytoexit!");    fclose(in);    getch();    exit(0);  }  while(!feof(

6、in))/*加密*/  {    fputc(encrypt(fgetc(in),n),out);  }  printf("Encryptisover!");  fclose(in);  fclose(out);  sleep(1);  }  if(ch0=='2')  {  clrscr();                    printf("Pleaseinputtheinfile:");  scanf("%s",infile);/*输入需要解密的文件名*/                        if((in=fopen(infile,"r"))=

7、=NULL)  {    printf("Cannotopentheinfile!");    printf("Pressanykeytoexit!");    getch();    exit(0);  }  printf("Pleaseinputthekey:");  scanf("%d",&n);/*输入解密密码（可以为加密时候的密码）*/  n=26-n;  printf("Pleaseinputtheoutfile:");  scanf("%s",outfile);/*输入解密后文件的