As a small experiment, I wrote an elementary C program to display min and max values of the basic object types.
/* Display min/max limits using limits.h header file */
#include <stdio.h> /* printf */
#include <limits.h> /* limits */
#include <assert.h> /* assert */
#define COMPUTE 1
/* used values:
*
* 0 - do not calculate min/max values
* 1 - calculate min/max values with exceptions for "long" types
* 2 - calculate min/max values without any exceptions */
/* calculate max value */
#define max(var, temp) \
var=0; temp=0; \
while((++var)>0) \
temp++;
/* calculate min value */
#define min(var, temp) \
var=0; temp=0; \
while((--var)<0) \
temp--;
/* print description and min/max limits using limits.h */
#define describe(description, type, min, max) \
printf("%s\n\tlimits.h: <%" type ", %" type ">\n", \
description, min, max);
/* calculate and print min/max values */
#define calculate(var, type, vmin, vmax) \
min(var, vmin); \
max(var, vmax); \
printf("\tcalculated: <%" type ", %" type ">\n", \
vmin, vmax);
int main()
{
/* signed char */
describe("signed char", "hhd", SCHAR_MIN, SCHAR_MAX);
# if COMPUTE
signed char schar, schar_max, schar_min;
calculate(schar, "hhd", schar_min, schar_max);
assert(schar_min == SCHAR_MIN && schar_max == SCHAR_MAX);
# endif
/* unsigned char */
describe("unsigned char", "hhu", 0, UCHAR_MAX);
# if COMPUTE
unsigned char uchar, uchar_min, uchar_max;
calculate(uchar, "hhu", uchar_min, uchar_max);
assert(uchar_min == 0 && uchar_max == UCHAR_MAX);
# endif
/* char */
describe("char", "hhd", CHAR_MIN, CHAR_MAX);
# if COMPUTE
char character, char_min, char_max;
calculate(character, "hhd", char_min, char_max);
assert(char_min == CHAR_MIN && char_max == CHAR_MAX);
# endif
/* signed short int */
describe("signed short int", "hd", SHRT_MIN, SHRT_MAX);
# if COMPUTE
signed short int ssint, ssint_min, ssint_max;
calculate(ssint, "hd", ssint_min, ssint_max);
assert(ssint_min == SHRT_MIN && ssint_max == SHRT_MAX);
# endif
/* unsigned short int */
describe("unsigned short int", "hu", 0, USHRT_MAX);
# if COMPUTE
unsigned short int usint, usint_min, usint_max;
calculate(usint, "hu", usint_min, usint_max);
assert(usint_min == 0 && usint_max == USHRT_MAX);
# endif
/* signed long int */
describe("signed long int", "ld", LONG_MIN, LONG_MAX);
# if COMPUTE == 2
signed long int slint, slint_min, slint_max;
calculate(slint, "ld", slint_min, slint_max);
assert(slint_min == LONG_MIN && slint_max == LONG_MAX);
# endif
/* unsigned long int */
describe("unsigned long int", "lu", (unsigned long int) 0, ULONG_MAX);
# if COMPUTE == 2
unsigned long int ulint, ulint_min, ulint_max;
calculate(ulint, "lu", ulint_min, ulint_max);
assert(ulint_min == 0 && ulint_max == ULONG_MAX);
# endif
#if defined __USE_ISOC99 && defined __GNUC__
/* signed long long int */
describe("signed long long int", "lld", LLONG_MIN, LLONG_MAX);
# if COMPUTE == 2
signed long long int sllint, sllint_min, sllint_max;
calculate(sllint, "lld", sllint_min, sllint_max);
assert(sllint_min == LLONG_MIN && sllint_max == LLONG_MAX);
# endif
/* unsigned long long int */
describe("unsigned long long int", "llu", \
(unsigned long long int) 0, ULLONG_MAX);
# if COMPUTE == 2
unsigned long long int ullint, ullint_min, ullint_max;
calculate(ullint, "llu", ullint_min, ullint_max);
assert(ullint_min == 0 && ullint_max == ULLONG_MAX);
# endif
#endif
/* signed int */
describe("signed int", "d", INT_MIN, INT_MAX);
# if COMPUTE
signed int sint, sint_min, sint_max;
calculate(sint, "d", sint_min, sint_max);
assert(sint_min == INT_MIN && sint_max == INT_MAX);
# endif
/* unsigned int */
describe("unsigned int", "u", 0, UINT_MAX);
# if COMPUTE
unsigned int uint, uint_min, uint_max;
calculate(uint, "u", uint_min, uint_max);
assert(uint_min == 0 && uint_max == UINT_MAX);
# endif
return 0;
}Sample output:
$ gcc limits.c -o limits
$ ./limits
signed char
limits.h: <-128, 127>
unsigned char
limits.h: <0, 255>
char
limits.h: <-128, 127>
signed short int
limits.h: <-32768, 32767>
unsigned short int
limits.h: <0, 65535>
signed long int
limits.h: <-9223372036854775808, 9223372036854775807>
unsigned long int
limits.h: <0, 18446744073709551615>
signed long long int
limits.h: <-9223372036854775808, 9223372036854775807>
unsigned long long int
limits.h: <0, 18446744073709551615>
signed int
limits.h: <-2147483648, 2147483647>
unsigned int
limits.h: <0, 4294967295>
Sample output (ISO C90 standard):
$ gcc -std=c89 limits.c -o limits
$ ./limits
signed char
limits.h: <-128, 127>
unsigned char
limits.h: <0, 255>
char
limits.h: <-128, 127>
signed short int
limits.h: <-32768, 32767>
unsigned short int
limits.h: <0, 65535>
signed long int
limits.h: <-9223372036854775808, 9223372036854775807>
unsigned long int
limits.h: <0, 18446744073709551615>
signed int
limits.h: <-2147483648, 2147483647>
unsigned int
limits.h: <0, 4294967295>
To calculate min and max values, modify the COMPUTE constant in the source code.
$ gcc limits.c -o limits
$ ./limits
signed char
limits.h: <-128, 127>
calculated: <-128, 127>
unsigned char
limits.h: <0, 255>
calculated: <0, 255>
char
limits.h: <-128, 127>
calculated: <-128, 127>
signed short int
limits.h: <-32768, 32767>
calculated: <-32768, 32767>
unsigned short int
limits.h: <0, 65535>
calculated: <0, 65535>
signed long int
limits.h: <-9223372036854775808, 9223372036854775807>
unsigned long int
limits.h: <0, 18446744073709551615>
signed long long int
limits.h: <-9223372036854775808, 9223372036854775807>
unsigned long long int
limits.h: <0, 18446744073709551615>
signed int
limits.h: <-2147483648, 2147483647>
calculated: <-2147483648, 2147483647>
unsigned int
limits.h: <0, 4294967295>
calculated: <0, 4294967295>
Read about -fno-strict-overflow and -fwrapv arguments if you want to use gcc optimization flags.
$ gcc -Os -fwrapv limits.c -o limits