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Create Caesar Ciper.c #3

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73 changes: 73 additions & 0 deletions Caesar Ciper.c
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Original file line number Diff line number Diff line change
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#include<ctype.h>
#include <stdlib.h>
#include<stdio.h>
#include<string.h>

typedef char* string;

//Declaration of Encryping and Number Checker Function
string encryptCaesar(string plainText, int key);
int isNumber(string s);

int main(int argc, string argv[])
{
//Check for Command Line Arguments
int key = 0;
if (argc == 2 && isNumber(argv[1]))
{
key = atoi(argv[1]);
}
else
{
printf("Usage: ./caesar key\n");
return 1;
}

//Getting Plain Text from User
string plainText;
printf("plaintext: ");
gets(plainText);

//Getting Caesar Cipher by Calling method
string cipherText = encryptCaesar(plainText, key);
printf("ciphertext: %s\n", cipherText);
return 0;
}

//Definition of Caesar Ciper Function
string encryptCaesar(string plainText, int key)
{
string cipherText = malloc(sizeof(plainText));
for (int i = 0, n = strlen(plainText); i <= n; i++)
{
if (plainText[i] >= 97 && plainText[i] <= 122)
{
int a = ((int)plainText[i] - 97 + key) % 26;
cipherText[i] = (int)(97 + a);
}
else if (plainText[i] >= 65 && plainText[i] <= 90)
{
int a = ((int)plainText[i] - 65 + key) % 26;
cipherText[i] = (int)(65 + a);
}
else
{
cipherText[i] = plainText[i];
}
}
return cipherText;
}

//Function for Checking Number
int isNumber(string s)
{
for (int i = 0, n = strlen(s); i < n; i++)
{
if (!isdigit(s[i]))
{
return 0;
}
}
//checking for non negative keys
return atoi(s) > 0;
}