One line is being skipped in file with isalpha() - c

Question

I am using isalpha() to determine if there are characters on the line and it is showing that the line "90 1 0" contains alphabetic characters.
Here is the relevant code
bool digitTest(char *test, int arysize)
{
int i;
for (i =0; i<arysize; i++)
{
if ((isalpha(test[i])) != 0){
return 0;
}
if (i==arysize)
return 1;
i++;
}
return 1;
}
It is called here
char buffer[4096] = {};
while(NULL!=fgets(buffer, sizeof(buffer), fp)){
if (digitTest(buffer, 4096) == 0){
printf ("contains alpha\n");
continue;
/*printing code if there is no alphabetic characters below, i do not believe it is relevant*/
and this is output
1
1
1
contains alpha
contains alpha
contains alpha
25123.90
54321.23
6
and input
1
1
1
89 23.5 not a number
90 1 0
-5.25 not a number 10000
25123.90 54321.23 6

Answer 1

The code has a few problems:
You shouldn't check all buffer. Check buffer until \0. because the output of fgets is a C-style string.
Second problem is an extra i++ in function digitTest. You should remove it.
You don't need arysize any more.
Use this digitTest function instead
int digitTest(char *test)
{
int i;
for (i=0; test[i] && test[i] != '\n'; i++)
{
if (isalpha(test[i]) != 0)
return 0;
}
return 1;
}
(maybe has minor bugs, I didn't test it)
And call it like this:
while( fgets(buffer, sizeof(buffer), fp) ) {
if (!digitTest(buffer)) {
printf ("contains alpha\n");
continue;
}
}

Answer 2

It Looks like you might be accessing locations in memory that contain characters, Change your code to
char buffer[4096] = {};
memset(buffer, 0, 4096);
while(NULL!=fgets(buffer, sizeof(buffer), fp)){
if (digitTest(buffer, strlen(buffer)) == 0){ //get actual length of buffer
printf ("contains alpha\n");
continue;
EDIT
In order to make your code not respond to either \n or \r do
bool digitTest(char *test, int arysize)
{
int i;
for (i =0; i<arysize; i++)
{
if( test[i] == '\r' || test[i] == '\n')
return 1;
if ((isalpha(test[i])) != 0){
return 0;
}
if (i==arysize)
return 1;
}
return 1;
}