simple java(六)---while

while
例一.

public class Sum1To10 {

public static void main( String args[] ) {

int i;

int sum = 0;

i = 1;

while ( i <= 10) {

sum += i;

i++;}

System.out.println( "Sum from 1 to 10 is "+ sum );

執行結果:

Sum from 1 to 10 is 55

等本人解釋一下上面個程式電腦點RUN

首先,我地SET左 i=1,電腦先會CHECK下while ( i <= 10), i係唔係<=10,如果係

的話..電腦就會做下一步驟sum += i;sum 本來係0.變了1,之後電腦就執行i++,

把i+1=2,根住電腦又CHECK下i=2,i係唔係<=10,如果係 的話..電腦就會做下一

步驟.....如此類推,如果唔係 的話,程式結束.

例二.

public class Sum1To10Tracing {

public static void main( String args[] ) {

int i;

int sum = 0;

i = 1;

while ( i <= 10) {

sum += i;

System.out.println( "i = " + i + ", sum = " + sum);

i++;}

System.out.println( "After running the loop, i = " + i );

System.out.println( "Sum from 1 to 10 is " + sum );}}

執行結果:

i = 1, sum = 1

i = 2, sum = 3

i = 3, sum = 6

i = 4, sum = 10

i = 5, sum = 15

i = 6, sum = 21

i = 7, sum = 28

i = 8, sum = 36

i = 9, sum = 45

i = 10, sum = 55

After running the loop, i = 11

Sum from 1 to 10 is 55