This article was previously published under Q89131
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LEN_TRIM may appear to return an incorrect trimmed string length. Thisoccurs when the string in the calling routine is not initialized and thesubprogram's formal argument declares the character string smaller than theoriginal string's length.
All bytes in uninitialized strings are set to zero (null characters). Whena string is initialized, any unused bytes are padded with spaces to the endof the string. The padding is done to the size that is declared in theroutine in which the string is initialized. If a string is passed to aroutine that declares the string size to be smaller then it was defined,the string will be incompletely padded with spaces. Upon return to theroutine where the string was declared, the string will still have nullcharacters at the end. The LEN_TRIM intrinsic function only parses forspaces and will stop immediately when it detects the final null character.This will appear to be incorrect because most editors display nullcharacters as blanks.
LEN_TRIM works correctly if the string lengths are declared equal in allroutines that the use the string. Also, initializing the string to allspaces in the routine in which it is originally declared will also correctthe problem.
Code to Reproduce Problem
character work*80 integer len call getstr(work) len = LEN_TRIM(work) print *,len ! len will be 80 end subroutine getstr(outstr) character outstr*45 outstr = 'This is a test' return end
Code to Correct Problem
character work*80 integer len work = ' ' call getstr(work) len = LEN_TRIM(work) print *,len ! len will be 14 end subroutine getstr(outstr) character outstr*45 outstr = 'This is a test' return end