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CS50 Problem Set 2 (Fall 2019) - Substitution
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//CS50 Problem Set 2 (Fall 2019): Substitution | |
//Author: teeschorle | |
#include <stdio.h> | |
#include <cs50.h> | |
#include <string.h> | |
#include <ctype.h> | |
bool validate(string key); | |
int main(int argc, string argv[]) | |
{ | |
if (argc == 2) | |
{ | |
string key = argv[1]; | |
if (validate(key) == true) | |
{ | |
string plaintext = get_string("plaintext: "); | |
int charcount = strlen(plaintext); | |
char ciphertext[charcount]; | |
string abc = "abcdefghijklmnopqrstuvwxyz"; | |
for (int i = 0; i < charcount; i++) | |
{ | |
if (isupper(plaintext[i]) != 0) | |
{ | |
for (int j = 0; j < 26; j++) | |
{ | |
if(abc[j] == tolower(plaintext[i])) | |
{ | |
ciphertext[i] = toupper(key[j]); | |
break; | |
} | |
} | |
} | |
else if (islower(plaintext[i]) != 0) | |
{ | |
for (int j = 0; j < 26; j++) | |
{ | |
if(abc[j] == plaintext[i]) | |
{ | |
ciphertext[i] = tolower(key[j]); | |
break; | |
} | |
} | |
} | |
else | |
{ | |
ciphertext[i] = plaintext[i]; | |
} | |
} | |
printf("ciphertext: %s\n", ciphertext); | |
return 0; | |
} | |
else | |
{ | |
printf("Please make sure your key is a permutation of all 26 characters - not more, not less.\n"); | |
return 1; | |
} | |
} | |
else | |
{ | |
printf("Input error. Please provide a single key.\n"); | |
return 1; | |
} | |
} | |
bool validate(string key) | |
{ | |
int matches = 0; | |
if (strlen(key) == 26) | |
{ | |
for (char c = 'a'; c <= 'z'; c++) | |
{ | |
for (int i = 0; i < 26; i++) | |
{ | |
if(tolower(key[i]) == c) | |
{ | |
matches++; | |
break; | |
} | |
} | |
} | |
if(matches == 26) | |
{ | |
return true; | |
} | |
else | |
{ | |
return false; | |
} | |
} | |
else | |
{ | |
return false; | |
} | |
} |
#include <stdio.h>
#include <cs50.h>
#include <ctype.h>
#include <string.h>
bool validate_key(string key);
int main(int argc, string argv[])
{
//checks if key is the right length
if (argc != 2 || strlen(argv[1]) != 26 || validate_key((string) argv[1]) != 1)
{
printf("Key must exist and contain 26 non identical alphabetical characters.\n");
return 1;
}
//gets input text
string text = get_string("plaintext: ");
int len = strlen(text);
char mychar = toupper(text[0]) - 65;
for (int i = 0; i < len; i++)
{
if (mychar >= 0 && mychar <= 26)
{
if (isupper(text[i]))
{
text[i] = toupper((char) argv[1][(int) mychar]);
}
else
{
text[i] = tolower((char) argv[1][(int) mychar]);
}
}
mychar = toupper(text[i + 1]) - 65;
}
printf("ciphertext: %s\n", text);
return 0;
}
bool validate_key (string key)
{
int len = strlen(key);
char mychar;
for(int i = 0; i < len; i++)
{
mychar = toupper(key[i]);
if(mychar >= 65 && mychar <= 90)
{
for(int j = i + 1; j < len; j++)
{
if(mychar == toupper(key[j]))
{
return 0;
}
}
}
else
{
return 0;
}
}
return 1;
}
#include <stdio.h>
#include <cs50.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
//get the input from the user in comomand-line
int main (int argc, string argv[])
{
if (argc == 2) // Checks if it is two arugument including file name
{
int len = strlen(argv[1]);
for (int i = 0; i < len; i++) // Checks if it is a digit, if yes, then print the following
{
if (isdigit(argv[1][i]))
{
printf("Usage: ./substitution key \n");
exit(0); // To terminate the program immediately
}
}
if (len != 26) // Checks if the length of the given input in command-line is 26 characters, if not, then print
{
printf("key must contain 26 characters.");
}
string plain = get_string("Plain text: "); //Get plain text from the user to encode it
string cipher;
printf("Cipher text: ");
for (int i = 0, n = strlen(plain); i < n; i++)
{
if (islower(plain[i])) // Checks the case sensitive
{
printf("%c", tolower(argv[1][plain[i] - 'a'])); // prints lower case cipher calue
}
else if (isupper(plain[i]))
{
printf("%c", toupper(argv[1][plain[i] - 'A'])); //prints upper case cipher value
}
else
{
printf("%c", plain[i]); // prints apart from alphabetical characters
}
}
}
else
{
printf("Usage: ./substitution key");
}
}
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#include <cs50.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, string argv[])
{
if (argc != 2 || !isalpha(*argv[1]))
{
printf("Usage: ./sub key\n");
return (1);
}
string key = argv[1];
if (strlen(key) != 26)
{
printf("Usage: ./sub key\n");
return (1);
}
string s = get_string("Plaintext: ");
printf("Ciphertext: ");
for (int i = 0, n = strlen(s); i < n; i++)
{
if (isupper(s[i]))
{
char u = s[i];
char m = 'A';
if (islower(s[i]))
m = 'a';
printf("%c",key[u - m] );
}
else
{
printf("%c",s[i]);
}
}
printf("\n");
return(0);
}