急求用c/c++对字符串加密解密的简单程序(有注释更好)

Question

用c/c++对字符串加密解密的简单程序(有注释更好)

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
Encrypt(char* cSrc,char* cDest)
{
char c;
int i,h,l,j=0;
for (i=0;i<(int)strlen(cSrc);i++)
{
c=cSrc[i];
h=(c>>4)&0xf;
l=c&0xf;
cDest[j]=h+'x';
cDest[j+1]=l+'z';
j+=2;
}
cDest[j]='\0';
return 0;
}
Decrypt(char* cSrc,char* cDest)
{
int i,h,l,m,n,j=0;
for (i=0;i<(int)strlen(cSrc);i=i+2)
{
h=(cSrc[i]-'x');
l=(cSrc[i+1]-'z');
m=(h<<4);
n=(l&0xf);
cDest[j]=m + n;
j++;
}
cDest[j]='\0';
return 0;
}
main(int argc, char *argv[])
{
char dest1[128]="\0";
char dest2[128]="\0";
char src[128]="\0";
printf("请输入源字符串：");
scanf("%s",src);
Encrypt(src,dest1);
printf("加密后的字符串为：%s\n",dest1);
Decrypt(dest1,dest2);
printf("还原后的字符串为：%s\n",dest2);
printf("长度为：%d\n",strlen(dest2));
return 0;
}

Answer 2

开头不说了
如果p=x *注x代指某实数或整数
则n=(p++)++运行结果是:
n=x+1,p=x+2

Answer 3

#include <stdio.h>

char* encrypt(char* str)
{
char* p = str;
int i = 0;
while(*p != '\0')
*p++ ^= i++;
return str;
}

char* decrypt(char* str)
{
char* p = str;
int i = 0;
while(*p != '\0')
*p++ ^= i++;
return str;
}

int main(void)
{
char str[] = "just test";
printf("%s\n", str);
printf("%s\n", encrypt(str));
printf("%s\n", decrypt(str));
return 0;
}