fortran指针

A pointer is a

variable that has the pointer attribute.A pointer is associated with a target by allocation

or pointer assignment

具有target属性的变量，可以用指针指向该变量

program mainimplicit noneinteger,pointer ::a=>null(),b=>null()integer,target ::cinteger ::d  c=1  print*,associated(a)  a=>c  c=2  b=>c  d=a+b  print*,associated(a)  print*,a,b,c,dend

输出 2 2 2 4

The associated intrinsic returns the association status of a pointer variable

associated返回T or F，如果指针已与变量关联返回T，否则返回F

integer , pointer :: a=>null(),b=>null()

allocate(a)

a = 1

如果我们没有allocate a那么对a进行赋值是非法的

program mainimplicit noneinteger,pointer ::a=>null(),b=>null()integer,target ::cinteger ::d  allocate(a)  allocate(b)  a=100  b=200  print*,a,b  c=1  a=>c  c=2  b=>c  d=a+b  print*,a,b,c,dend

输出100 200

2 2 2 4

ALLOCATE ( allocation-list [ , STAT = stat-variable ] )

If the STAT= specifier is present, successful execution of the ALLOCATE statement causes the stat-variable to

become defined with a value of zero. If an error condition occurs during the execution of the ALLOCATE

statement, the stat-variable becomes defined with a processor-dependent positive integer value.

References

Ian Chivers / Jane Sleightholme 

Introduction to Programming with Fortran-With Coverage of Fortran 90, 95, 2003, 2008 and 77    

f90 stanard：http://www.fortran.com/f90_std.pdf