<limits.h>        -        Sizes of integral types

This library supplies machine-dependant macros that define the range of integer and character types.

jump to : example of <limits.h>

1	CHAR_BIT	8	number of bits in char
2	CHAR_MIN	(-128)	minimum if signed char, otherwise (0)
3	CHAR_MAX	127	maximum if signed char, otherwise (255)
4	MB_LEN_MAX	1	multiple byte lenght - maximum 1 byte
5	SCHAR_MAX	127	maximum signed char
6	SCHAR_MIN	(-128)	minimum signed char
7	UCHAR_MAX	255	maximum unsigned char
8	SHRT_MAX	32767	maximum short integer
9	SHRT_MIN	-32767-1	minimum short integer
10	USRT_MAX	65535U	maximum unsigned short integer
11	INT_MAX	32767	maximum integer
12	INT_MIN	-32767-1	minimum integer
13	UNIT_MAX	0XFFFFU	maximum unsigned integer
14	LONG_MAX	2147483647L	maximum long integer
15	LONG_MIN	(-2147483647L-1)	mimimum long integer
16	ULONG_MAX	4294967295UL	maximum unsigned long integer

Example:

This example will print the maximum and minimum value of the data type specifier int. Note that this can depend on the OS and compiler being used.

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

int main(void)
{
    printf("The maximum value of INT can be %d\n", INT_MAX);

    printf("The minimum value of INT can be %d\n", INT_MIN);

    return 0;
}

The reason why these values can be different than the ones shown in the table above, are due mainly to the OS being used. When these limits were set back in the 70's, most people didn't predict that OS's would ever be as complex as they are now (modern OS's are 32-bit and even 64-bit).

These values were designed for the 16-bit operating system hence maxium range for int was assumed to be 2^16 (2 to the power of 16). 2^16 == (256*256) divided by 2 (for negative and positive ) and -1 for the positive range (0 is considered positive) gives an answer of 32767 - the MAX_INT. Since modern OS's are 32 bit, the range is now 2^32 not 2^16 - the range increases to 4294967295 - divide by 2 and substract 1 - and the maximum value of int becomes 2147483647 (the value printed out if you are using a modern version windows or linux or equivalent).

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