1. #include  <stdio.h>
    2. int SUM(int num1, int num2){
    3.     return num1 * num2;
    5. }     
    6. int main(){
    8.     int n[] ={1,2,3,4,5,6,7,11,13};
    9.     int len = sizeof(n) / sizeof n[0] ;
    12.     int SUM1 = 20;
    13.     int sum2 = 16;
    15.     int c;
    17.     for ( int i = 0; i < len; i ++){
    18.         for ( int j = j +1; j < len; j++){
    19.             c = c + 1;
    21.             if  (n[i] + n[j] == SUM1){
    23.                 printf("[%d] : %d * %d = %d\n", c, n[i], n[j], SUM1);
    25.             }
    27.         }
    29.     }    
    32. printf("[%d] ： （n[%d] + n[%d]) = SUM1\n", c,  SUM1);
    34.  return 0;
    36. }

    3ae9511ac7ee1f768102e09c2eb48d0.png
    预习设计的不成功