Thread: Help with simple encode program

This is a simple casear cipher encode only portion that i wrote. it:

1. Promtps for user input
2. Asks for the shift value
3. Uses the shift value such as 2 on the first letter then increments it by 1 for each letter after that.
EXAMPLE: Hello would be Jhpqu


My problem is at the end of each encrypted word it prints a funny character that i dont need. How can i eliminate it??thanks

Code:

#include <stdio.h>
#include <string.h>


   



/*encode function, to encode user input */
int main()
{
	char buff[BUFSIZ];
	int i = 0;
	int shift_value;
	int p = 0;

    printf( "**initializing.....**\n\n"
	        "**linking..........**\n\n");
	printf( "Welcome agent Brown\n\n");
	printf( "You have accessed the Caesar Cipher program\n\n");
	printf("\nPlease enter the text you wish to encrypt: ");/*accept user input */
	fgets(buff, sizeof(buff), stdin);

	
	printf("\nEnter your encryption shift value (anything from +-1 to 25): "); 
    scanf ("%i", &shift_value);

	{	
			while ( buff[i] != '\0'  )
			{
				
				buff[i] = buff[i] + shift_value + i++;
				
				 }
		
	}

	printf("\n Your encrypted text is:%s\n",buff);/*return encrypted text */

	
	return 0; /* indicate successful completeion */
}

oh the wonders of being a noob. I tried adjusting the code in the link and utilizing it in my code in different parts, but now it doesnt return anything. i dont get any text back now.

Code:

#include <stdio.h>
#include <string.h>


   



/*encode function, to encode user input */
int main()
{
	char buff[BUFSIZ];
	int i = 0;
	int shift_value;
	int p = 0;
	char *r;

    printf( "**initializing.....**\n\n"
	        "**linking..........**\n\n");
	printf( "Welcome agent Brown\n\n");
	printf( "You have accessed the Caesar Cipher program\n\n");
	printf("\nPlease enter the text you wish to encrypt: ");/*accept user input */
	fgets(buff, sizeof(buff), stdin);

	
	printf("\nEnter your encryption shift value (anything from +-1 to 25): "); 
    scanf ("%i", &shift_value);

	{	
			while ( buff[i] != '\0'  )
			{
				
				buff[i] = buff[i] + shift_value + i++;
				
				 }
		
	}
	if (fgets(buff, sizeof(buff), stdin) != NULL)
	{
		if ((r = strchr(buff, '\n')) != NULL)
		*r = '\0';

		printf("\nYour encrypted text is:%s\n",buff);/*return encrypted text */

	}
	return 0; /* indicate successful completeion */
}

arg, yes, and i just noticed this line i have in there.

Code:

while ( buff[i] != '\0'  )

thats evidently not going to work anymore.
How could i take that out or modify it and get the code to work?

hmm this is what i have now. the character at the end from the newline is gone but now the first 2 letters are funny shapes??

Code:

#include <stdio.h>
#include <string.h>


   



/*encode function, to encode user input */
int main()
{
	char buff[BUFSIZ];
	int i = 0;
	int shift_value;
	int p = 0;
	char *r;

    printf( "**initializing.....**\n\n"
	        "**linking..........**\n\n");
	printf( "Welcome agent Brown\n\n");
	printf( "You have accessed the Caesar Cipher program\n\n");
	printf("\nPlease enter the text you wish to encrypt: ");/*accept user input */
	fgets(buff, sizeof(buff), stdin);
	if (fgets(buff, sizeof(buff), stdin) != NULL)
	{
		if ((r = strchr(buff, '\n')) != NULL)
		*r = '\0';
	}


	
	printf("\nEnter your encryption shift value (anything from +-1 to 25): "); 
    scanf ("%i", &shift_value);

	{	
			while ( buff[i] != '\n'  )
			{
				
				buff[i] = buff[i] + shift_value + i++;
				
				 }
		
	}
	
		printf("\nYour encrypted text is:%s\n",buff);/*return encrypted text */

	
	return 0; /* indicate successful completeion */
}

> buff[i] = buff[i] + shift_value + i++;
You'd be much better off if you didn't have undefined operations in your code either.

Just simplify to
buff[i] = buff[i] + shift_value + i;
i++;

i do have the habit of jumping ahead of myself without paying attention. This is just so overwhelming right now. Hopefully with more practice i can not fret so much about writing these programs.

I understand the for loop makes more sense. But what would i be checking for, i have tested a few ideas to no avail. I either get back no text, or 1 funny character.

Code:

	{	
		for(??? )
			{

			  buff[i] = buff[i] + shift_value + i;
			  i++;
				
			}
		
	}