C语言凯撒移位加密算法

c语言编写，欢迎扔板砖 //移位算法 #include #include #define SIZE 50 int main() { //i 用于计数输入个数，j 为临时变量， plain 存放明文， cipher 存放密文，decryption存放解密后文本，fpp 为明文文件指针，fpc 为密文文件指针 int i,j; char plain[SIZE],cipher[SIZE],decryption[SIZE],ciphertext[SIZE]; FILE * fpp,* fpc,* fpd; //加密 //建立新的明文TXT文件 printf("Caesar algorithm\n"); if((fpp=fopen("plain.txt","w+"))==NULL) { printf("creat new plain file error!\n"); exit(0); } //输入明文 printf("input plain alphabet:\n"); i=0; scanf("%c",&plain[i]); while(plain[i]!='\n'&&i122) { cipher[j]=cipher[j]%122+96; printf("cipher %d = %c\n",j,cipher[j]); } else if(cipher[j]>90) { cipher[j]=cipher[j]%90+64; printf("cipher %d = %c\n",j,cipher[j]); } else { printf("cipher %d = %c\n",j,cipher[j]); } } //建立密文文件 if((fpc=fopen("cipher.txt","w+"))==NULL) { printf("create new cipher file error!"); exit(0); } for(j=0;j