第16-19课作业第一题

第一小题

#include <stdio.h>#include <stdlib.h>//第一题，第一小题int main(){int i;int a[20] = {1,2,3,4,5,6,7,8,9,0};  //初始化前10个元素//键盘输入后10个元素的值for (i = 10; i < 20; i++)scanf("%d", &a[i]);//由前往后输出数组中所有元素的值printf("由前往后，数组中的值是：\n");for (i = 19; i >= 0; i--)printf("%2d", a[i]);return 0;}

第二小题

#include <stdio.h>#include <stdlib.h>//第一题，第二小题int main(){int i;int a[10] = {1,2,3,4,5,6,7,8,9,0};  //初始化printf("由后往前，数组中的值是：\n");for (i = 9; i >=0; i--)printf("%d ",a[i]);for (i = 0; i < 10; i++)a[i] *= 2;printf("\n");printf("由后往前，数组中的值修改后是：\n");for (i = 9; i >= 0; i--)printf("%d ", a[i]);return 0;}

第三小题

#include <stdio.h>#include <stdlib.h>//第一题，第三小题int main(){int i;int a[16] = {1,2,3,4,5,6,7,8,9,0,1,2,3,4,6,7};  //初始化printf("数组中，元素值为3的倍数的元素和值为：\n");for (i = 0; i < 16; i++){if (a[i] % 3 == 0)printf("a[%d] %d\n", i, a[i]);}printf("\n");return 0;}

第四小题

#include <stdio.h>#include <stdlib.h>//第一题，第四小题int main(){int i,j;int count_del=0;int a[16] = {1,2,3,4,5,6,7,8,9,0,1,2,3,4,6,7};  //初始化for (i = 0; i < 16-count_del; i++){if (a[i] % 3 == 0){for (j = i; j < 16 - count_del; j++)a[j] = a[j + 1];//将被删除的元素后面的值依次移动count_del++;a[16 - count_del] = 0;//最后一位移除的数据用0置空i--;//注意,因为将后一项的数据移动了过来，如果不减一的话，将会少计算一项}}for (i = 0; i < 16 - count_del; i++)printf("%d ", a[i]);printf("\n");return 0;}

第五小题

#include <stdio.h>#include <stdlib.h>//第一题，第五小题int main(){int i,j;int count_del=0;int a[16] = {1,2,3,4,5,6,7,8,9,0,1,2,3,4,6};  //初始化for (i = 15; i >= 1; i--)a[i] = a[i - 1];printf("请输入一个数字：");scanf("%d", &a[0]);for (i = 0; i < 16; i++)printf("%d ", a[i]);printf("\n");return 0;}