編號:N49817024

1

12

123

1234

12345

123456

1234567

12345678

123456789

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int a,b;
    for(a=1; a<=9; a++)
    {
      for(b=1; b<=a; b++)
      {
       printf("%d",b);
      }
     printf("\n");
    }
    system("PAUSE");
    return 0;
}

 int a,b;                            宣告a,b為可變函數

 for(a=1; a<=9; a++)      (外迴圈)預設a值在1~9之間,控制縱軸

 for(b=1; b<=a; b++)      (內迴圈)預設b值1~b<=a之間,控制橫軸

邏輯:

for(a=1; a<=9; a++)
for(b=1; b<=a; b++)

a=1 ,b=1<=a                                                                印出"1"

a=2 ,b=1<=a ,b=2<=a                                                 印出"1" ,"2"

a=3 ,b=1<=a ,b=2<=a ,b=3<=a                                  印出"1" ,"2" ,"3"

             .

             .

             .                  

            以此類推

當a=某數 ,b的條件<=a的條件時,就會將某數(包括其它未符合<=a的數字)印出

for(a=1; a<=9; a++)
    {
      for(b=1; b<=a; b++)
      {
       printf("%d",b);                                  //將b值印出
      }
     printf("\n");                                         //跳下一列                              
    }

  *參考資料:圖解C語言(書)

 *以上為個人學習經驗,請參考書籍