Character and String Classification

Custom functions to classify characters or validate string content. More...

Files
file	ft_check.h
	Classification and validation functions for characters and strings.
file	ft_is_valid_integer.c
	Validates whether a string represents a valid long long integer.

Functions
bool	ft_is_valid_integer (const char *str)
	Validates C-style signed integer string format.
int	ft_isalnum (int c)
	Alphanumeric character.
int	ft_isalpha (int c)
	Alphabetic character.
int	ft_isascii (int c)
	ASCII character (0–127)
int	ft_isdigit (int c)
	Decimal digit (0–9)
int	ft_islower (int c)
	Lowercase letter.
int	ft_isprint (int c)
	Printable character (including space)
int	ft_ispunct (int c)
	Printable non-alphanumeric (e.g., punctuation)
int	ft_issign (int c)
	'+' or '-'
int	ft_isspace (int c)
	Whitespace (space, tab, newline, etc.)
bool	ft_isstrpositive (const char *str)
	Checks if string contains only digits and is > 0.
int	ft_isupper (int c)
	Uppercase letter.
static bool	is_in_longlong_range (const char *str, bool negative)
	Checks if a numeric string fits within the long long range.

Detailed Description

Custom functions to classify characters or validate string content.

This group includes replacements and enhancements for standard <ctype.h> checks as well as boolean helpers to test string-wide properties (e.g., numeric strings, positivity).

This group includes:

• ft_isalnum
• ft_isalpha
• ft_isascii
• ft_isdigit
• ft_isprint
• ft_ispunct
• ft_isspace
• ft_islower
• ft_isupper
• ft_issign
• ft_isstrpositive
• ft_is_valid_integer

Function Documentation

ft_is_valid_integer()

bool ft_is_valid_integer

(

const char *

str

)

#include <include/ft_check.h>

Validates C-style signed integer string format.

Validates if a string represents a valid long long integer.

The string may start with a '+' or '-' sign, followed by decimal digits. The function rejects empty strings, non-digit characters, and any numeric values that would overflow a long long.

Parameters

str	Null-terminated string to validate.

Returns

true if valid, false otherwise.

See also

is_in_longlong_range

ft_isalnum()

int ft_isalnum

(

int

c

)

#include <include/ft_check.h>

Alphanumeric character.

Checks if a character is alphanumeric.

Parameters

c	Character to check.

Returns

1 if alphabetic or digit, otherwise 0.

ft_isalpha()

int ft_isalpha

(

int

c

)

#include <include/ft_check.h>

Alphabetic character.

Checks if a character is an alphabetic letter.

Parameters

c	Character to check.

Returns

1 if 'A'–'Z' or 'a'–'z', otherwise 0.

ft_isascii()

int ft_isascii

(

int

c

)

#include <include/ft_check.h>

ASCII character (0–127)

Checks if a character is an ASCII character.

Parameters

c	Character to check.

Returns

1 if ASCII (0–127), otherwise 0.

ft_isdigit()

int ft_isdigit

(

int

c

)

#include <include/ft_check.h>

Decimal digit (0–9)

Checks if a character is a decimal digit.

Parameters

c	Character to check.

Returns

1 if '0'–'9', otherwise 0.

ft_islower()

int ft_islower

(

int

c

)

#include <include/ft_check.h>

Lowercase letter.

Checks if a character is lowercase.

Parameters

c	Character to check.

Returns

1 if 'a'–'z', otherwise 0.

ft_isprint()

int ft_isprint

(

int

c

)

#include <include/ft_check.h>

Printable character (including space)

Checks if a character is printable.

Parameters

c	Character to check.

Returns

1 if printable (32–126), otherwise 0.

ft_ispunct()

int ft_ispunct

(

int

c

)

#include <include/ft_check.h>

Printable non-alphanumeric (e.g., punctuation)

Checks if a character is a punctuation mark.

Parameters

c	Character to check.

Returns

1 if punctuation, otherwise 0.

ft_issign()

int ft_issign

(

int

c

)

#include <include/ft_check.h>

'+' or '-'

Checks if a character is a sign symbol.

Parameters

c	Character to check.

Returns

1 if '+' or '-', otherwise 0.

ft_isspace()

int ft_isspace

(

int

c

)

#include <include/ft_check.h>

Whitespace (space, tab, newline, etc.)

Checks if a character is a whitespace character.

Recognized: space, tab, newline, vertical tab, form feed, carriage return.

Parameters

c	Character to check.

Returns

1 if whitespace, otherwise 0.

ft_isstrpositive()

bool ft_isstrpositive

(

const char *

str

)

#include <include/ft_check.h>

Checks if string contains only digits and is > 0.

Checks if a string represents a positive number.

Returns 1 if the string exists, is non-empty, and does not start with '-'.

Parameters

str	Null-terminated string to check.

Returns

1 if positive, otherwise 0.

ft_isupper()

int ft_isupper

(

int

c

)

#include <include/ft_check.h>

Uppercase letter.

Checks if a character is uppercase.

Parameters

c	Character to check.

Returns

1 if 'A'–'Z', otherwise 0.

is_in_longlong_range()

static bool is_in_longlong_range ( const char *  str, bool  negative  )

static

#include <srcs/check/ft_is_valid_integer.c>

Checks if a numeric string fits within the long long range.

This helper function verifies whether the numeric value represented by the string (without sign prefix) is within the bounds of a signed long long, depending on whether it's negative.

Uses manual overflow detection logic to avoid undefined behavior.

Parameters

str	The numeric string to check (must not include the sign).
negative	Indicates if the original number was negative.

Returns

true if the value fits in long long, false otherwise.

See also

ft_isdigit