The malloc() function is called by:
k = malloc( n ) |
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n |
INTEGER |
Input |
Number of bytes of memory |
Return value |
INTEGER(Cray POINTER) |
Output |
k>0: k = address of the start of the block of memory allocated k=0: Error |
An INTEGER*8 pointer value is returned when compiled for a 64-bit environment with -m64. See Note below. |
This function is intrinsic in Fortran 95 and was external in Fortran 77. Fortran 77 programs compiled to run in 64-bit environments would declare the malloc() function and the variables receiving its output as INTEGER*8. The function malloc64(3F) was provided to make programs portable between 32-bit and 64-bit environments.
k = malloc64( n ) |
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n |
INTEGER*8 |
Input |
Number of bytes of memory |
Return value |
INTEGER*8 (Cray POINTER) |
Output |
k>0: k=address of the start of the block of memory allocated k=0: Error |
These functions allocate an area of memory and return the address of the start of that area. (In a 64-bit environment, this returned byte address may be outside the INTEGER*4 numerical range—the receiving variables must be declared INTEGER*8 to avoid truncation of the memory address.) The region of memory is not initialized in any way, and it should not be assumed to be preset to anything, especially zero!
Example: Code fragment using malloc():
parameter (NX=1000) integer ( p2X, X ) real*4 X(1) … p2X = malloc( NX*4 ) if ( p2X .eq. 0 ) stop ’malloc: cannot allocate’ do 11 i=1,NX 11 X(i) = 0. … end |
In the above example, we acquire 4,000 bytes of memory, pointed to by p2X, and initialize it to zero.