Advanced UNIX Programming

Large Integer Conversions

With the migration of UNIX systems to 64-bit CPUs, the C language now supports 64-bit integers. These data types are

• long long int

• unsigned long long int

or simply

• long long

• unsigned long long

With the appearance of these C data types comes the need to make conversions from strings to these 64-bit types.

Some UNIX platforms now support the strtoll(3) and strtoull(3) functions. Their synopsis is as follows:

#include <stdlib.h>

long long strtoll(const char *str, char **endptr, int base);

unsigned long long strtoull (const char *str, char **endptr, int base);

These functions work the same as their strtol(3) and strtoul(3) counterparts. The only difference is that you must use the macro LONGLONG_MAX or LONGLONG_MIN when ...