Integer Numbers in Programming Language

An integer variable may be defined to be of type short, int, or long. The only difference is that an int uses more or at least the same number of bytes as a short, and a long uses more or at least the same number of bytes as an int. For example, on the author’s PC, a short uses 2 bytes, an int also 2 bytes, and a long 4 bytes.

short age = 20;

int salary = 65000;

long price = 4500000;

By default, an integer variable is assumed to be signed (i.e., have a signed representation so that it can assume positive as well as negative values). However, an integer can be defined to be unsigned by using the keyword unsigned in its definition. The keyword signed is also allowed but is redundant.

unsigned short age = 20;

unsigned int salary = 65000;

unsigned long price = 4500000;

A literal integer (e.g., 1984) is always assumed to be of type int, unless it has an L or l suffix, in which case it is treated as a long. Also, a literal integer can be specified to be unsigned using the suffix U or u. For example:

1984L 1984l 1984U 1984u 1984LU 1984ul

Literal integers can be expressed in decimal, octal, and hexadecimal notations. The decimal notation is the one we have been using so far. An integer is taken to be octal if it is preceded by a zero (0), and hexadecimal if it is preceded by a 0x or 0X. For example:

92 // decimal

0134 // equivalent octal

0x5C // equivalent hexadecimal

Octal numbers use the base 8, and can therefore only use the digits 0-7. Hexadecimal numbers use the base 16, and therefore use the letter A-F (or a-f) to represent, respectively, 10-15. Octal and hexadecimal numbers are calculated as follows:

0134 = 1 × 82 + 3 × 81 + 4 × 80 = 64 + 24 + 4 = 92

0x5C = 5 × 161 + 12 × 160 = 80 + 12 = 92