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vigenere.c
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/
vigenere.c
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/**
*Introduction to Computer Science
*
*CS50
*
*PSET 2
*VIGENERE CIPHER
*
*coder: 4ndr4a
****/
#include<stdio.h>
#include<cs50.h>
#include<string.h>
#include<ctype.h>
#include<stdlib.h>
string ciph(string text, string k);
int main(int argc, char* argv[])
{
//Rejects less than or more than 2 arguments
while(argc != 2)
{
printf("Error!\n");
return 1;
}
string k = argv[1];
//Check the Key: anything but letters is rejected
for(int m = 0, n = strlen(k); m < n; m++)
{
if(ispunct(k[m]) || isdigit(k[m]))
{
printf("Error!\n");
return 1;
}
}
string text = GetString();
//calling of the ciphering function
string citext = ciph(text,k);
printf("%s", citext);
printf("\n");
return 0;
}
//Ciphering Function
string ciph(string text, string k)
{
//Encription engine
for(int i = 0, j = 0; i < strlen(k) && j < strlen(text);)
{
if(isupper(text[j]) && islower(k[i]))
{
if(text[j] == 90)
{
text[j] = text[j] + k[i] - 97 - 25;
i++;
j++;
}
else if(isblank(text[j]) || isdigit(text[j]) || ispunct(text[j]))
{
j++;
}
else
{
if(text[j] + k[i] <= 187)
{
text[j] = text[j] + k[i] - 97;
i++;
j++;
}
else
{
text[j] = text[j] + k[i] - 97 - 26;
}
}
}
else if(isupper(text[j]) && isupper(k[i]))
{
if(text[j] == 90)
{
text[j] = text[j] + k[i] - 65 - 25;
i++;
j++;
}
else if(isblank(text[j]) || isdigit(text[j]) || ispunct(text[j]))
{
j++;
}
else if(text[j] + k[i] <= 155)
{
text[j] = text[j] + k[i] - 65;
i++;
j++;
}
else
{
text[j] = text[j] + k[i] - 65 - 26;
i++;
j++;
}
}
else if(islower(text[j]) && isupper(k[i]))
{
if(text[j] == 122)
{
text[j] = text[j] + k[i] - 65 - 25;
i++;
j++;
}
else if(isblank(text[j]) || isdigit(text[j]) || ispunct(text[j]))
{
j++;
}
else
{
if(text[j] + k[i] <= 187)
{
text[j] = text[j] + k[i] - 65;
i++;
j++;
}
else
{
text[j] = text[j] + k[i] - 65 - 26;
i++;
j++;
}
}
}
else
{
if(text[j] == 122)
{
text[j] = text[j] + k[i] - 97 - 25;
i++;
j++;
}
else if(isblank(text[j]) || isdigit(text[j]) || ispunct(text[j]))
{
j++;
}
else
{
if(text[j] + k[i] <= 219)
{
text[j] = text[j] + k[i] - 97;
i++;
j++;
}
else
{
text[j] = text[j] + k[i] - 97 - 26;
i++;
j++;
}
}
}
if(i == strlen(k))
{
i = 0;
}
}
return text;
}