"run.sh error line 31" on check50

Question

jharvard@appliance (~/Dropbox/pset2): check50 2014/x/pset2/caesar caesar.c
:) caesar.c exists
:) caesar.c compiles
:( encrypts "a" as "b" using 1 as key
   \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
:( encrypts "barfoo" as "yxocll" using 23 as key
   \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
:( encrypts "BARFOO" as "EDUIRR" using 3 as key
   \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
:( encrypts "BaRFoo" as "FeVJss" using 4 as key
   \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
:( encrypts "barfoo" as "onesbb" using 65 as key
   \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 214..."
:( encrypts "world, say hello!" as "iadxp, emk tqxxa!" using 12 as key
   \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
:) handles lack of argv[1]
https://sandbox.cs50.net/checks/2f449728b97446c58778fc95360f4897
jharvard@appliance (~/Dropbox/pset2): ./caesar 1
a
b
jharvard@appliance (~/Dropbox/pset2): ./caesar 3
BARFOO
EDUIRR
jharvard@appliance (~/Dropbox/pset2): 

Answer 1

Make sure that your check contains upper and lower cases. Check print, if you added "(argument)\n" , its possible to get wrong. If you have that remove \n and make you program to print new line at the end. You might wanna take some notes to: 1. What will happen if you don't have argv..You should exit the program or retry until argv is filled with positive number. 2. Does you program handles symbols like '\' or ' '.. you should print that symbols the same as the user type them.

I hope this will help you.

Answer 2

Change your initial condition to

if (argc != 2)

rather than if (argc == 1), because you want to return an error every time the user has not provided exactly 2 arguments.

No need to initialise "x = 0" outside your for loop, because you can do so within the initialisation of the loop. Don't forget to provide the data type though:

for(int x = 0; ...)

Make your for loop more efficient by letting it count strlen() only once:

for(int x = 0, y = strlen(plain); x < y; x++)

Regarding your nested loops, you should work on the following:

First, check whether plain[x] is a letter or not by using the isalpha() function.

Second, if isalpha() returns true, check whether plain[x] is uppercase or lowercase by using the isupper() and islower() functions. - Are either of these conditions met, you can include your code for encryption here.

Third, If isalpha() is not met, you do not want to encrypt anything, so include a statement such as

else
{
    printf("%c", plain[x]);
}

Finally, you don't need an if statement that breaks the loop if x >= strlen(plain), because due to the condition you have set in your outer for loop, the latter will not execute if x takes on this value.