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Nov 24 2024
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[ Loops | Conditions | Jumps ]
ICM contains a complete set of control statements to allow looping, jumping and conditional branching.Loops |
Two types of loops are allowed, namely for-loop and while-loop.
For-loop
for <i_index> = <i_from> , <i_to> [, <i_increment> ] ... ... endfor
While-loop
while( <logical_expression> ) ... ... endwhile
Examples:
for i = 1, 9
print "ICM-shell proudly announces that i=" i
endfor
for i = 1, 4
print "ICM-shell proudly announces that i=" i
for j = 1, 3
print "ICM-shell proudly announces that nesting is possible and j=" j
endfor
endfor
read object "crn"
for i = 1, Nof(a_/*) # Nof(a_/*) means 'the number of residues'
print Label(a_/$i)
endfor
i = -2
while (i != 4)
i = i+1
print i
endwhile
while(yes)
print "endless loop, please wait 8-)"
endwhile
Any number of nested loops may be used.
Conditional branching |
Several types of conditional statements are allowed in the ICM-shell.
if
if ( <logical_expression> ) <command>
if-then-endif
if ( <logical_expression> ) then
...
...
endif
if-then-elseif-..else-endif
if( <logical_expression> ) then
...
else
...
endif
or
if ( <logical_expression> ) then ... elseif ( <logical_expression> ) then ... elseif ( <logical_expression> ) then ... else ... endifNote: end if or else if (instead of endif or elseif ) are not accepted by ICM-shell.
Examples:
JohnnySaid = "The gloves didn't fit" if ( JohnnySaid == "The gloves didn't fit" ) print "You must acquit" # grade = "bad" if (grade == "excellent") then print "It's great!" elseif (grade == "good") then print "It's good!" elseif (grade == "bad") then print "It's not so bad!" # do not be harsh on your kids endif
Jumps |
Three types of jump controls are possible, namely commands break, continue and goto. break interrupts the loop, continue skips commands until the nearest endfor or endwhile and continues looping, and goto jumps to any point below.
break
<for-loop> or <while-loop>
...
if ( <logical expression> ) break
...
<end of loop>
continue
<for-loop> or <while-loop>
...
if ( <logical expression> ) continue
...
<end of loop>
goto
... if ( <logical expression> ) goto <label> ... ... <label>: ...
Examples:
for i = 1, 6
print "currently i=", i, "and it will be increased at the next step"
if (i == 3) then
print "... but at this point we should stop it, sorry..."
break
endif
endfor
print "end of the loop demonstrating *break*, bye"
for i = 1, 6
if (i == 3) then
print "... let us skip over step 3 and continue looping"
continue
endif
print "currently i=", i, "and it will be increased at the next step"
endfor
print "end of the loop demonstrating *continue*, bye"
for i = 1, 5
if (i == 3) then
print "... but at this point we decided to skip 3-rd step, sorry..."
goto A
endif
print "currently i=", i, "and it will be increased at the next step"
A: print " "
endfor
print "end of the loop demonstrating 'goto', bye"
Note: go to (instead of goto) is not accepted by the ICM-shell. Any combination of alphanumeric characters beginning with a letter (upper or lower case) may serve as a label. Also keep in mind that goto can jump only forward; the backward goto is not allowed.
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