Thread: Simple Encryption using an array

I am very new to programming so can someone please help with this problem.
I have managed to read a sentence into an array and changed all the characters to upper case now I have to move each character 3 places in the alphabet, so some kind of wrap around will be necessary. If you programme for a living don't worry about me stealing your job!!
Here is my code so far:

//Create an array.
//invite the user to key in a sentence.
//put the sentence into the array.
//Then using seperate functions....
//convert all the characters to upper case.
// encrypt the message by moving each character 3 places in the //alphabet.

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

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

{
char sentence[100];

printf ("Please enter a sentence and press enter:\n\n");

gets(sentence);

printf ("\nThe sentence you keyed in was:\n\n%s\n\n",sentence);

char *p;

for( p = sentence; p < sentence + strlen( sentence ); p++ )
{
if( islower( *p ) )
_putch( _toupper( *p ) );

else
_putch( *p );
}

}

I don't know if this works but...

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

int main(void) {

char algo[100];
int i = 0;

strcpy(algo, "Anda a la casa de tu tia");

while (algo[i] != '\0') {
algo[i] = algo[i] + 1;
i++;
}
printf("%s", algo);
}

Thanks Garfield

I am aware that I require a function and have tried to write one, however it will only work up to the letter 'w', here is the updated code: by the way the previous code didn't work as strcpy wasn't identified.....

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

{
char sentence[100];

printf ("Please enter a sentence and press enter:\n\n");

gets(sentence);

printf ("\nThe sentence you keyed in was:\n\n%s\n",sentence);
printf ("\n\nThe sentence in Uppercase is:\n\n");

char *p;

for( p = sentence; p < sentence + strlen( sentence ); p++ )
{
if( islower( *p ) )
_putch( _toupper( *p ) );

else
_putch( *p );
}

printf ("\n\nThe sentence Encrypted is:\n\n");


for( p = sentence; p < sentence + strlen( sentence ); p++ )
{
if( islower( *p ) )

if(isalpha( *p ) )
_putch( _toupper( *p +3) );

else
_putch( _toupper( *p ) );

else

if(isalpha( *p ) )
_putch( *p +3);

else
_putch( *p );

}

printf ("\n\n");
}