Unsigned(category25-plesk.html) - phpMan

strtoul (3)          - convert a string to an unsigned long integer
strtoul (3p)         - convert a string to an unsigned long
strtoull (3)         - convert a string to an unsigned long integer
strtoull (3p)        - convert a string to an unsigned long
strtouq (3)          - convert a string to an unsigned long integer
wcstoul (3p)         - convert a wide-character string to an unsigned long
wcstoull (3p)        - convert a wide-character string to an unsigned long