isalnum

Your mission

Implement gm_isalnum, your own isalnum, which reports whether a single character is alphanumeric: a letter or a decimal digit.

See it in action

gm_isalnum('a')

Expected result

Your checklist

For your own tracking. Tests grade your code.

Return a non-zero value when c is a letter (a-z or A-Z) or a decimal digit (0-9).
Return 0 for every other character, including spaces, punctuation, and the zero byte.
Think of it as the union of two checks: is it a letter, OR is it a digit. Test each range with its own bounds.
Watch the boundaries: @ sits just before A and [ just after Z in ASCII, so a loose comparison can wrongly accept them.

More examples

gm_isalnum('7')

Expected result

gm_isalnum('@')

Expected result

Constraints

Expected files

isalnum.c

Allowed functions

None. Write every helper yourself.

libc

Standard C library

Implements the contract of a function from the standard C library.

isalnum

Characters and ASCII

Your mission

Implement gm_isalnum, your own isalnum, which reports whether a single character is alphanumeric: a letter or a decimal digit.

See it in action

gm_isalnum('a')

Expected result

Your checklist

For your own tracking. Tests grade your code.

Return a non-zero value when c is a letter (a-z or A-Z) or a decimal digit (0-9).
Return 0 for every other character, including spaces, punctuation, and the zero byte.
Think of it as the union of two checks: is it a letter, OR is it a digit. Test each range with its own bounds.
Watch the boundaries: @ sits just before A and [ just after Z in ASCII, so a loose comparison can wrongly accept them.

More examples

gm_isalnum('7')

Expected result

gm_isalnum('@')

Expected result

Constraints

Expected files

isalnum.c

Allowed functions

None. Write every helper yourself.

libc

Standard C library

Implements the contract of a function from the standard C library.

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01Zero byteWaiting

02Lowercase letterWaiting

03Uppercase letterWaiting

04Decimal digitWaiting

05Space is not alphanumericWaiting

06Punctuation is not alphanumericWaiting

07Boundary just before 'A'Waiting

08Boundary just after 'Z'Waiting

isalnum

Your mission

Implement gm_isalnum, your own isalnum, which reports whether a single character is alphanumeric: a letter or a decimal digit.

See it in action

gm_isalnum('a')

Expected result

Your checklist

For your own tracking. Tests grade your code.

Return a non-zero value when c is a letter (a-z or A-Z) or a decimal digit (0-9).
Return 0 for every other character, including spaces, punctuation, and the zero byte.
Think of it as the union of two checks: is it a letter, OR is it a digit. Test each range with its own bounds.
Watch the boundaries: @ sits just before A and [ just after Z in ASCII, so a loose comparison can wrongly accept them.

More examples

gm_isalnum('7')

Expected result

gm_isalnum('@')

Expected result

Constraints

Expected files

isalnum.c

Allowed functions

None. Write every helper yourself.

libc

Standard C library

Implements the contract of a function from the standard C library.

isalnum

Characters and ASCII

Your mission

Implement gm_isalnum, your own isalnum, which reports whether a single character is alphanumeric: a letter or a decimal digit.

See it in action

gm_isalnum('a')

Expected result

Your checklist

For your own tracking. Tests grade your code.

Return a non-zero value when c is a letter (a-z or A-Z) or a decimal digit (0-9).
Return 0 for every other character, including spaces, punctuation, and the zero byte.
Think of it as the union of two checks: is it a letter, OR is it a digit. Test each range with its own bounds.
Watch the boundaries: @ sits just before A and [ just after Z in ASCII, so a loose comparison can wrongly accept them.

More examples

gm_isalnum('7')

Expected result

gm_isalnum('@')

Expected result

Constraints

Expected files

isalnum.c

Allowed functions

None. Write every helper yourself.

libc

Standard C library

Implements the contract of a function from the standard C library.

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01Zero byteWaiting

02Lowercase letterWaiting

03Uppercase letterWaiting

04Decimal digitWaiting

05Space is not alphanumericWaiting

06Punctuation is not alphanumericWaiting

07Boundary just before 'A'Waiting

08Boundary just after 'Z'Waiting