tolower

Your mission

Implement gm_tolower, your own tolower, which converts a single uppercase letter to its lowercase form and returns every other value untouched.

See it in action

gm_tolower('A')

Expected result

Your checklist

For your own tracking. Tests grade your code.

If c is an uppercase letter (A to Z), return its lowercase equivalent.
For any other value, already-lowercase letters, digits, spaces, and symbols, return c unchanged.
Work on the character codes directly: a lowercase letter sits exactly 32 positions after its uppercase form in ASCII.
Guard the range first. Blindly adding 32 or OR-ing in 0x20 also mangles non-letters like @ and [, which must pass through as-is.

More examples

gm_tolower('z')

Expected result

gm_tolower('7')

Expected result

Constraints

Expected files

tolower.c

Allowed functions

None. Write every helper yourself.

libc

Standard C library

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

tolower

Characters and ASCII

Your mission

Implement gm_tolower, your own tolower, which converts a single uppercase letter to its lowercase form and returns every other value untouched.

See it in action

gm_tolower('A')

Expected result

Your checklist

For your own tracking. Tests grade your code.

If c is an uppercase letter (A to Z), return its lowercase equivalent.
For any other value, already-lowercase letters, digits, spaces, and symbols, return c unchanged.
Work on the character codes directly: a lowercase letter sits exactly 32 positions after its uppercase form in ASCII.
Guard the range first. Blindly adding 32 or OR-ing in 0x20 also mangles non-letters like @ and [, which must pass through as-is.

More examples

gm_tolower('z')

Expected result

gm_tolower('7')

Expected result

Constraints

Expected files

tolower.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

01Uppercase A becomes aWaiting

02Uppercase Z becomes zWaiting

03Already lowercase is unchangedWaiting

04Digit is unchangedWaiting

05Space is unchangedWaiting

06Symbol is unchangedWaiting

07Character just before A is unchangedWaiting

08Character just after Z is unchangedWaiting

tolower

Your mission

Implement gm_tolower, your own tolower, which converts a single uppercase letter to its lowercase form and returns every other value untouched.

See it in action

gm_tolower('A')

Expected result

Your checklist

For your own tracking. Tests grade your code.

If c is an uppercase letter (A to Z), return its lowercase equivalent.
For any other value, already-lowercase letters, digits, spaces, and symbols, return c unchanged.
Work on the character codes directly: a lowercase letter sits exactly 32 positions after its uppercase form in ASCII.
Guard the range first. Blindly adding 32 or OR-ing in 0x20 also mangles non-letters like @ and [, which must pass through as-is.

More examples

gm_tolower('z')

Expected result

gm_tolower('7')

Expected result

Constraints

Expected files

tolower.c

Allowed functions

None. Write every helper yourself.

libc

Standard C library

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

tolower

Characters and ASCII

Your mission

Implement gm_tolower, your own tolower, which converts a single uppercase letter to its lowercase form and returns every other value untouched.

See it in action

gm_tolower('A')

Expected result

Your checklist

For your own tracking. Tests grade your code.

If c is an uppercase letter (A to Z), return its lowercase equivalent.
For any other value, already-lowercase letters, digits, spaces, and symbols, return c unchanged.
Work on the character codes directly: a lowercase letter sits exactly 32 positions after its uppercase form in ASCII.
Guard the range first. Blindly adding 32 or OR-ing in 0x20 also mangles non-letters like @ and [, which must pass through as-is.

More examples

gm_tolower('z')

Expected result

gm_tolower('7')

Expected result

Constraints

Expected files

tolower.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

01Uppercase A becomes aWaiting

02Uppercase Z becomes zWaiting

03Already lowercase is unchangedWaiting

04Digit is unchangedWaiting

05Space is unchangedWaiting

06Symbol is unchangedWaiting

07Character just before A is unchangedWaiting

08Character just after Z is unchangedWaiting