isdigit

Characters and ASCII12

Objective

Implement a function that reports whether a character is one of the decimal digits 0 through 9.

Steps

Return a non-zero value when c is a decimal digit (0 to 9), and 0 otherwise.
A character is just a small integer: the digits 0..9 sit next to each other in the ASCII table, so a single range check is enough.
Mind the boundaries, / comes right before 0 and : right after 9. Neither is a digit.
Hex letters like a or F are not decimal digits here, even though they look numeric in other contexts.

examples

$ isdigit('7')

$ isdigit('a')

$ isdigit(':')

Constraints

Expected files

isdigit.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

01First digit '0'

02Middle digit '5'

03Last digit '9'

04Boundary '/' just before '0'

05Boundary ':' just after '9'

06Lowercase letter 'a'

07Hex letter 'F' is not a decimal digit

08Space character

isdigit

Objective

Implement a function that reports whether a character is one of the decimal digits 0 through 9.

Steps

Return a non-zero value when c is a decimal digit (0 to 9), and 0 otherwise.
A character is just a small integer: the digits 0..9 sit next to each other in the ASCII table, so a single range check is enough.
Mind the boundaries, / comes right before 0 and : right after 9. Neither is a digit.
Hex letters like a or F are not decimal digits here, even though they look numeric in other contexts.

examples

$ isdigit('7')

$ isdigit('a')

$ isdigit(':')

Constraints

Expected files

isdigit.c

Allowed functions

None. Write every helper yourself.

libc

Standard C library

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

isdigit

Characters and ASCII12

Objective

Implement a function that reports whether a character is one of the decimal digits 0 through 9.

Steps

Return a non-zero value when c is a decimal digit (0 to 9), and 0 otherwise.
A character is just a small integer: the digits 0..9 sit next to each other in the ASCII table, so a single range check is enough.
Mind the boundaries, / comes right before 0 and : right after 9. Neither is a digit.
Hex letters like a or F are not decimal digits here, even though they look numeric in other contexts.

examples

$ isdigit('7')

$ isdigit('a')

$ isdigit(':')

Constraints

Expected files

isdigit.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

01First digit '0'

02Middle digit '5'

03Last digit '9'

04Boundary '/' just before '0'

05Boundary ':' just after '9'

06Lowercase letter 'a'

07Hex letter 'F' is not a decimal digit

08Space character