qfedu-c-level/day10/homework/h15.c

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// 设计函数接收一个数值类型的5行3列的二维数组和查找的数值返回数值在二维数组的序号。
// 【提示】第一个元素的序号为0 第二行第一个元素的序号为3
#include <stdio.h>
int find(int (*arr)[3], int num)
{
int *p = arr[0]; // arr[0] == &arr[0][0]
// int *p = &arr[0][0]; // arr[0] == &arr[0][0]
int n = 0;
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 3; j++)
{
// if (arr[i][j] == num)
if (*(p + i * 3 + j) == num) // arr[i][j] == *(p+i*3+j)
{
return n;
}
n++; // 序号加1
}
}
return -1; // 没找到
}
int main()
{
int a[5][3] = {
{1, 2, 3},
{4, 5, 6},
{7, 9, 9},
{10, 11, 12},
{13, 14, 15}};
printf("%d\n", find(a, 9)); // 输出结果7
return 0;
}