long varname = INIT _ VALUE；

First, the type keyword of long integer in C language is long. When defined, var_name is the variable name. INIT_VALUE is an initialization value and can be omitted. No initialization value is defined as:

long var _ name

Second, write a single long, which is expressed as a single long integer. In fact, two default keywords, sung and int, are omitted. Please write the full text as follows:

Signed long variable name;

But a single long is a signed long integer by default, so signed and int are generally omitted.

Third, the definition of unsigned long integers needs to be written as follows:

Unsigned long variable name;

4. Long type accounts for 4 bytes. In the case of sign, the expression range is-2147483648 ~ 2147483647. In the case of unsigned, the representation range is 0~4294967295.

5. In formatted input and output, the format string of signed long integer is "%ld" and the format string of unsigned long integer is "%lu".