Noob to c programming help!

 

// This function will shift the character by the determined amount 

// For our purpose we are only concerned with the letters a - z 

char ShiftCharacter(char unencrypt,int shift_value,int offset) 

{ 

char encrypted_char = unencrypt; 

int i; 

 

// Capital A - Z 

if(unencrypt >= 'A' && unencrypt <= 'Z') 

{ 

	for( i = 0; i < (shift_value + offset); i++) 

	{ 

		encrypted_char++; 

		if(encrypted_char > 'Z') 

		{ 

			encrypted_char = 'A'; 

		} 

	} 

 

} 

 

// Lowercase a - z 

else if(unencrypt >= 'a' && unencrypt <= 'z') 

{ 

	for( i = 0; i < (shift_value + offset); i++) 

	{ 

		encrypted_char++; 

		if(encrypted_char > 'z') 

		{ 

			encrypted_char = 'a'; 

		} 

	} 

} 

 

return encrypted_char; 

 

} 

 

 

// casear_cipher.cpp : Defines the entry point for the console application. 

// 

 

#include "stdafx.h" 

#include tdio.h>  

#include tring.h> 

 

// Declare the function 

char ShiftCharacter(char unencrypt,int shift_value,int offset); 

 

 

int main(int argc, char* argv[]) 

{ 

 

	char buff[1024];  

	int shift_value;  

	int encrypt_text_length; 

	int i; 

 

	// Say hello  

	puts("**initializing.....**\n\n**linking..........**\n\n");  

	puts("Welcome agent Brown\n\n");  

	puts("You have accessed the Caesar Cipher program\n\n");  

	puts("Please enter the text you wish to encrypt: "); 

 

	// Get input from the user 

	// It is possible that the user may exceed our allocated space. 

	// We could address that but it would cloud the issue. TODO: for later 

	scanf("%s",&buff);   

 

	puts("\nEnter your encryption shift value (anything from +-1 to 25): ");  

	scanf("%d",&shift_value);  

 

	// We now have a string and a shift value 

	// TODO: Check for empty string and out of range value 

 

 

	// Determine how long the string is 

	encrypt_text_length = strlen(buff); 

 

	// Encrypted the text 

	for(i = 0; i < encrypt_text_length; i++) 

	{ 

		buff = ShiftCharacter(buff,shift_value,i);  

	}  

 

	// Display the encrypted text for the user 

	printf("\nYour encrypted text is: %s",buff);  

 

 

	return 0; /* indicate successful completeion */  

} 

 

 

// This function will shift the character by the determined amount 

// For our purpose we are only concerned with the letters a - z 

char ShiftCharacter(char unencrypt,int shift_value,int offset) 

{ 

char encrypted_char; 

int alphanumber; // The character as a number ( A = 1, B = 2, Z = 26 etc.) 

 

// Capital A - Z 

if(unencrypt >= 'A' && unencrypt <= 'Z') 

{ 

	alphanumber = unencrypt - 'A'; 

	alphanumber += shift_value + offset; 

	alphanumber = (alphanumber % 26); 

	encrypted_char  = (char)(alphanumber + 'A'); 

 

} 

 

// Lowercase a - z 

else if(unencrypt >= 'a' && unencrypt <= 'z') 

{ 

	alphanumber = unencrypt - 'a'; 

	alphanumber += shift_value + offset; 

	alphanumber = (alphanumber % 26); 

	encrypted_char  = (char)(alphanumber + 'a'); 

} 

 

return encrypted_char; 

 

} 

 

 

[edit on 10-12-2005 by dbates]