delphi语法基础-循环语句（Delphi语法基础-循环语句）.docVIP

delphi语法基础-循环语句（Delphi语法基础-循环语句） Delphi syntax base - loop statement 2008-09-16 PM 01:46 format For control variables: = initial value, to, final value, do statement; For control variables: = initial value, downto, final value, do statement; For statement execution process: 1. Assign the initial value to the left variable (called the loop control variable); 2, to determine whether the value of the loop control variable has exceeded the final value, if more than, jump to step 5; 3, the end of the fruit exceeds the final value, then execute the statement after do (called loop body); 4. The control variable returns step 2; 5, loop end, execute for cycle statement. Explain： The loop control variable must be of order type. For example, they can be integers, characters, etc., but not real. The value of the cyclic control variable is increased by to, while the downto is decreased. The value of the loop control variable exceeds the final value. For the increasing cycle, the over is greater than the decreasing cycle, and the over index is less than. Once the initial and final values of the loop control variables are determined, the number of cycles is determined. However, modifying the value of the loop variable in the loop often results in premature completion of the loop or into the dead ring. It is recommended that you do not modify the value of the control variables at the discretion of the loop. The initial and final values in a for statement can be constants, variables, expressions of a sequence type. Example 5_1, S = 1+2+3+... + 100 Var n I: integer {I} is a loop variable; S: Longint {s}; accumulator Begin Write (input, n=); readln (n); s:=0; For i:=2 to n do s:=s+i from 2 to N; {s} is added to Writeln (1+2+3+... + 100=, s); End. With 5_2, output of the first 20 Fibonacci sequence. Rule: F1=0 (n=1) F2=1 (n=2) Fn=Fn-1+Fn-2 (n=3) means 0, 1, 1, 2, 3,, 5, 8, 13, and 21,...... Analysis: by formula Fn=Fn-1+Fn-2, recursive algorithm is used to solve. Method one VaR, a, B, i