C Library - < limits.h >

The limits.h header determines various properties of the various variable types. The macros defined in this header, limits the values of various variable types like char, int and long.

These limits specify that a variable cannot store any value beyond these limits, for example an unsigned character can store up to a maximum value of 255.

Library Macros

The following values are implementation-specific and defined with the #define directive, but these values may not be any lower than what is given here.

Macro	Value	Description
CHAR_BIT	8	Defines the number of bits in a byte.
SCHAR_MIN	-128	Defines the minimum value for a signed char.
SCHAR_MAX	+127	Defines the maximum value for a signed char.
UCHAR_MAX	255	Defines the maximum value for an unsigned char.
CHAR_MIN	-128	Defines the minimum value for type char and its value will be equal to SCHAR_MIN if char represents negative values, otherwise zero.
CHAR_MAX	+127	Defines the value for type char and its value will be equal to SCHAR_MAX if char represents negative values, otherwise UCHAR_MAX.
MB_LEN_MAX	16	Defines the maximum number of bytes in a multi-byte character.
SHRT_MIN	-32768	Defines the minimum value for a short int.
SHRT_MAX	+32767	Defines the maximum value for a short int.
USHRT_MAX	65535	Defines the maximum value for an unsigned short int.
INT_MIN	-2147483648	Defines the minimum value for an int.
INT_MAX	+2147483647	Defines the maximum value for an int.
UINT_MAX	4294967295	Defines the maximum value for an unsigned int.
LONG_MIN	-9223372036854775808	Defines the minimum value for a long int.
LONG_MAX	+9223372036854775807	Defines the maximum value for a long int.
ULONG_MAX	18446744073709551615	Defines the maximum value for an unsigned long int.

Example

The following example shows the usage of few of the constants defined in limits.h file.

#include <stdio.h>
#include <limits.h>

int main() {

   printf("The number of bits in a byte %d\n", CHAR_BIT);

   printf("The minimum value of SIGNED CHAR = %d\n", SCHAR_MIN);
   printf("The maximum value of SIGNED CHAR = %d\n", SCHAR_MAX);
   printf("The maximum value of UNSIGNED CHAR = %d\n", UCHAR_MAX);

   printf("The minimum value of SHORT INT = %d\n", SHRT_MIN);
   printf("The maximum value of SHORT INT = %d\n", SHRT_MAX); 

   printf("The minimum value of INT = %d\n", INT_MIN);
   printf("The maximum value of INT = %d\n", INT_MAX);

   printf("The minimum value of CHAR = %d\n", CHAR_MIN);
   printf("The maximum value of CHAR = %d\n", CHAR_MAX);

   printf("The minimum value of LONG = %ld\n", LONG_MIN);
   printf("The maximum value of LONG = %ld\n", LONG_MAX);
  
   return(0);
}

Let us compile and run the above program that will produce the following result −

The maximum value of UNSIGNED CHAR = 255                                    
The minimum value of SHORT INT = -32768                                     
The maximum value of SHORT INT = 32767                                      
The minimum value of INT = -2147483648                                      
The maximum value of INT = 2147483647                                       
The minimum value of CHAR = -128                                            
The maximum value of CHAR = 127                                             
The minimum value of LONG = -9223372036854775808                            
The maximum value of LONG = 9223372036854775807