[問題] 同樣程式碼 執行結果怎麼會不一樣

[風雨同路共送呂布]

class Miracle
{
public static void main(String args[])
{
int Graph[][]={{0,1,1,1,0,0,0,0,0,0,0,0,1},{1,0,1,1,0,0,0,0,0,0,0,0,0},
{1,1,0,1,0,0,0,0,0,0,0,0,0},{1,1,1,0,1,1,0,0,0,0,0,0,1},
{0,0,0,1,0,1,1,0,0,0,0,0,0},{0,0,0,1,1,0,1,1,1,0,0,0,0},
{0,0,0,0,1,1,0,1,0,0,0,0,0},{0,0,0,0,0,1,1,0,1,0,0,0,0},
{0,0,0,0,0,1,0,1,0,1,0,0,0},{0,0,0,0,0,0,0,0,1,0,1,0,0},
{0,0,0,0,0,0,0,0,0,1,0,1,0},{0,0,0,0,0,0,0,0,0,0,1,0,0},
{1,0,0,1,0,0,0,0,0,0,0,0,0}
};
//執行這段程式碼 會跑出ArrayIndexoutOfBoundsexception
/*int i,j;
for(i=0;i<13;i++)
{
for(j=0;j<13;j++);
System.out.print(Graph[i][j]);
System.out.println();
}
*/

//若採用這段程式碼 卻是順利執行
//但這兩段程式明明是一模一樣的 怎麼會結果差很多
//這可以算是奇蹟嗎? 還是這兩段程式有不同之處?希望有人能解惑 謝謝
int i,j;
for(i=0;i<13;i++)
{
for(j=0;j<13;j++)
System.out.print(Graph[i][j]);
System.out.println();
}

}
}

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[風~]

※ 引述《Happyboy101 (風雨同路共送呂布)》之銘言：
: class Miracle
: {
: public static void main(String args[])
: {
: int Graph[][]={{0,1,1,1,0,0,0,0,0,0,0,0,1},{1,0,1,1,0,0,0,0,0,0,0,0,0},
: {1,1,0,1,0,0,0,0,0,0,0,0,0},{1,1,1,0,1,1,0,0,0,0,0,0,1},
: {0,0,0,1,0,1,1,0,0,0,0,0,0},{0,0,0,1,1,0,1,1,1,0,0,0,0},
: {0,0,0,0,1,1,0,1,0,0,0,0,0},{0,0,0,0,0,1,1,0,1,0,0,0,0},
: {0,0,0,0,0,1,0,1,0,1,0,0,0},{0,0,0,0,0,0,0,0,1,0,1,0,0},
: {0,0,0,0,0,0,0,0,0,1,0,1,0},{0,0,0,0,0,0,0,0,0,0,1,0,0},
: {1,0,0,1,0,0,0,0,0,0,0,0,0}
: };
: //執行這段程式碼 會跑出ArrayIndexoutOfBoundsexception
: /*int i,j;
: for(i=0;i<13;i++)
: {
: for(j=0;j<13;j++);
^^^你這裡多了分號@@
: System.out.print(Graph[i][j]);
: System.out.println();
: }
: */
: //若採用這段程式碼 卻是順利執行
: //但這兩段程式明明是一模一樣的 怎麼會結果差很多
: //這可以算是奇蹟嗎? 還是這兩段程式有不同之處?希望有人能解惑 謝謝
: int i,j;
: for(i=0;i<13;i++)
: {
: for(j=0;j<13;j++)
: System.out.print(Graph[i][j]);
: System.out.println();
: }
: }
: }

--
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[..]

※ 引述《Happyboy101 (風雨同路共送呂布)》之銘言：
: class Miracle
: {
: public static void main(String args[])
: {
: int Graph[][]={{0,1,1,1,0,0,0,0,0,0,0,0,1},{1,0,1,1,0,0,0,0,0,0,0,0,0},
: {1,1,0,1,0,0,0,0,0,0,0,0,0},{1,1,1,0,1,1,0,0,0,0,0,0,1},
: {0,0,0,1,0,1,1,0,0,0,0,0,0},{0,0,0,1,1,0,1,1,1,0,0,0,0},
: {0,0,0,0,1,1,0,1,0,0,0,0,0},{0,0,0,0,0,1,1,0,1,0,0,0,0},
: {0,0,0,0,0,1,0,1,0,1,0,0,0},{0,0,0,0,0,0,0,0,1,0,1,0,0},
: {0,0,0,0,0,0,0,0,0,1,0,1,0},{0,0,0,0,0,0,0,0,0,0,1,0,0},
: {1,0,0,1,0,0,0,0,0,0,0,0,0}
: };
: //執行這段程式碼 會跑出ArrayIndexoutOfBoundsexception
產生exception的原因：
因為你的內層迴圈直接在最後加上分號，表示迴圈並沒有執行任何程式
就一直累加直到j=13才跳出迴圈，執行System.out.println(Graph[i][j])
因為j=13，而你index的合法範圍為0~12，所以產生了exception
以上，就是問題所在
: /*int i,j;
: for(i=0;i<13;i++)
: {
: for(j=0;j<13;j++); //這段程式碼是會產生exception的地方
: System.out.print(Graph[i][j]);
: System.out.println();
: }
: */
: //若採用這段程式碼 卻是順利執行
: //但這兩段程式明明是一模一樣的 怎麼會結果差很多
: //這可以算是奇蹟嗎? 還是這兩段程式有不同之處?希望有人能解惑 謝謝

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