C defines minimum ranges for its fundamental integer types. The exact size and range of a type can vary between implementations, so programs should not assume that a type always has a particular size.

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

int main()
{
    printf("CHAR_BIT  = %d\n", CHAR_BIT);
    printf("CHAR_MIN  = %d\n", CHAR_MIN);
    printf("CHAR_MAX  = %d\n", CHAR_MAX);

    printf("INT_MIN   = %d\n", INT_MIN);
    printf("INT_MAX   = %d\n", INT_MAX);

    printf("LONG_MIN  = %ld\n", LONG_MIN);
    printf("LONG_MAX  = %ld\n", LONG_MAX);

    return 0;
}

Example Output #

On a typical implementation:

CHAR_BIT  = 8
CHAR_MIN  = -128
CHAR_MAX  = 127
INT_MIN   = -2147483648
INT_MAX   = 2147483647
LONG_MIN  = -9223372036854775808
LONG_MAX  = 9223372036854775807

Explanation #

The <limits.h> header provides macros describing implementation-defined limits for integer types.

For example:

printf("%d\n", INT_MAX);

prints the largest value that an int can represent on the implementation.

The actual limits should be obtained from <limits.h> rather than assumed from a particular compiler or processor.