Defined in header <math.h> #define isunordered(x, y) /* implementation defined */ (since C99) Determines if the floating point numbers x and y are unordered, that is, one or both are NaN and thus cannot be meaningfully compared with each other. Parameters x - floating point value y - floating point value Return value Nonzero integral value if either x or y is NaN, ​0​ otherwise. Example #include <stdio.h> #include <math.h> int main(voi

Defined in header <ctype.h> int isspace( int ch ); Checks if the given character is a whitespace character, i.e. either space (0x20), form feed (0x0c), line feed (0x0a), carriage return (0x0d), horizontal tab (0x09) or vertical tab (0x0b). The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF. Parameters ch - character to classify Return value Non-zero value if the character is a whitespace character, zero o

Defined in header <ctype.h> int ispunct( int ch ); Checks if the given character is a punctuation character in the current C locale. The default C locale classifies the characters !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~ as punctuation. The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF. Parameters ch - character to classify Return value Non-zero value if the character is a punctuation character, zero o

Defined in header <cctype> int isprint( int ch ); Checks if the given character can be printed, i.e. it is either a number (0123456789), an uppercase letter (ABCDEFGHIJKLMNOPQRSTUVWXYZ), a lowercase letter (abcdefghijklmnopqrstuvwxyz), a punctuation character(!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~), or space, or any character classified as printable by the current C locale. The behavior is undefined if the value of ch is not representable as unsigned char and is not equ

Defined in header <math.h> #define isnormal(arg) /* implementation defined */ (since C99) Determines if the given floating point number arg is normal, i.e. is neither zero, subnormal, infinite, nor NaN. The macro returns an integral value. FLT_EVAL_METHOD is ignored: even if the argument is evaluated with more range and precision than its type, it is first converted to its semantic type, and the classification is based on that. Parameters arg - floating point value

Defined in header <math.h> #define isnan(arg) /* implementation defined */ (since C99) Determines if the given floating point number arg is a not-a-number (NaN) value. The macro returns an integral value. FLT_EVAL_METHOD is ignored: even if the argument is evaluated with more range and precision than its type, it is first converted to its semantic type, and the classification is based on that (this matters if the evaluation type supports NaNs, while the semantic type does n

Defined in header <ctype.h> int islower( int ch ); Checks if the given character is classified as a lowercase character according to the current C locale. In the default "C" locale, islower returns true only for the lowercase letters (abcdefghijklmnopqrstuvwxyz). If islower returns true, it is guaranteed that iscntrl, isdigit, ispunct, and isspace return false for the same character in the same C locale. The behavior is undefined if the value of ch is not representable as u

Defined in header <math.h> #define islessgreater(x, y) /* implementation defined */ (since C99) Determines if the floating point number x is less than or greater than the floating-point number y, without setting floating-point exceptions. Parameters x - floating point value y - floating point value Return value Nonzero integral value if x < y || x > y, ​0​ otherwise. Notes The built-in operator< and operator> for floating-point numbers may

Defined in header <math.h> #define islessequal(x, y) /* implementation defined */ (since C99) Determines if the floating point number x is less than or equal to the floating-point number y, without setting floating-point exceptions. Parameters x - floating point value y - floating point value Return value Nonzero integral value if x <= y, ​0​ otherwise. Notes The built-in operator<= for floating-point numbers may raise FE_INVALID if one or both

Defined in header <math.h> #define isless(x, y) /* implementation defined */ (since C99) Determines if the floating point number x is less than the floating-point number y, without setting floating-point exceptions. Parameters x - floating point value y - floating point value Return value Nonzero integral value if x < y, ​0​ otherwise. Notes The built-in operator< for floating-point numbers may raise FE_INVALID if one or both of the arguments is