如何打印最大值和最小值的索引？

Question

以下代码打印最大值和最小值。我如何着手打印这些值的索引而不是值本身？

#include <stdio.h>

int main()
{
    int arr1[100];
    int i, mx, mn, n;   

       printf("Input the number of elements to be stored in the array :");
       scanf("%d",&n);

       printf("Input %d elements in the array :\n",n);
       for(i=0;i<n;i++)
            {
          printf("element - %d : ",i);
          scanf("%d",&arr1[i]);
        }


    mx = arr1[0];
    mn = arr1[0];

    for(i=1; i<n; i++)
    {
        if(arr1[i]>mx)
        {
            mx = arr1[i];
        }


        if(arr1[i]<mn)
        {
            mn = arr1[i];
        }
    }
    printf("Maximum element is : %d\n", mx);
    printf("Minimum element is : %d\n\n", mn);

    return 0;
}

Answer 1

分别更新 mx 时只需保存索引 mn:

int max_index = 0;
int min_index = 0;

// ...

    if(arr1[i]>mx)
    {
        mx = arr1[i];
        max_index = i;
    }


    if(arr1[i]<mn)
    {
        mn = arr1[i];
        min_index = i;
    }

Answer 2

作为上一个答案的替代方案，您可以使用指针和指针算法：

#include <stdio.h>

int main()
{
    int arr1[100];
    int i, n;
    int *mn, *mx;

    printf("Input the number of elements to be stored in the array :");
    scanf("%d", &n);

    printf("Input %d elements in the array :\n",n);
    for(i = 0; i < n; i++)
    {
        printf("element - %d : ", i);
        scanf("%d", &arr1[i]);
    }

    mx = &arr1[0];
    mn = &arr1[0];

    for(i = 1; i < n; i++)
    {
        if(arr1[i] > *mx)
            mx = &arr1[i];

        if(arr1[i] < *mn)
            mn = &arr1[i];
    }

    printf("Maximum element is : %d (%d)\n", *mx, mx - arr1);
    printf("Minimum element is : %d (%d)\n\n", *mn, mn - arr1);

    return 0;
}

示例：

$ gcc main.c -o main.exe; ./main.exe;
Input the number of elements to be stored in the array :5
Input 5 elements in the array :
element - 0 : 3
element - 1 : 2
element - 2 : 1
element - 3 : 5
element - 4 : 4
Maximum element is : 5 (3)
Minimum element is : 1 (2)

Answer 3

更改代码以跟踪最小和最大元素的索引并不难。

只需在变量 mx 和 mn 中存储相应的最小和最大元素的索引，而不是它们的值，例如。

mx = 0;
mn = 0;

for ( i = 1; i < n; i++ )
{
    if ( arr1[i] > arr1[mx] )
    {
        mx = i;
    }
    else if ( arr1[i] < mn )
    {
        mn = i;
    }
}

但我想指出的是，请始终尝试编写更通用的代码。

您可以编写一个单独的函数，returns 一对最大和最小元素的索引。

给你。

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

struct Pair { size_t min; size_t max; } 
minmax_element( const int a[], size_t n )
{
    struct Pair minmax = { .min = 0, .max = 0 };

    for ( size_t i = 1; i < n; i++ )
    {
        if ( a[i] < a[minmax.min] )
        {
            minmax.min = i;
        }
        else if ( a[minmax.max] < a[i] )
        {
            minmax.max = i;
        }
    }

    return minmax;
}

int main(void) 
{
    size_t n = 1;

    printf( "Input the number of elements to be stored in the array: " );
    scanf( "%zu", &n );

    int a[n];

    srand( ( unsigned int )time( NULL ) );

    for ( size_t i = 0; i < n; i++ )
    {
        a[i] = rand() % ( int )n;
    }

    for ( size_t i = 0; i < n; i++ )
    {
        printf( "%d ", a[i] );
    }
    putchar( '\n' );

    struct Pair minmax = minmax_element( a, n );

    printf( "The minimum value is %d at position %zu\n", a[minmax.min], minmax.min );
    printf( "The maximum value is %d at position %zu\n", a[minmax.max], minmax.max );

    return 0;
}

程序输出可能类似于

Input the number of elements to be stored in the array: 10
7 1 7 3 1 7 8 5 0 3 
The minimum value is 0 at position 8
The maximum value is 8 at position 6

或者，该函数可以定义两个附加参数：指向最小元素索引的指针和指向最大元素索引的指针。

给你。

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

void minmax_element( const int a[], size_t n, size_t *min, size_t *max )
{
    *min = 0;
    *max = 0;

    for ( size_t i = 1; i < n; i++ )
    {
        if ( a[i] < a[*min] )
        {
            *min = i;
        }
        else if ( a[*max] < a[i] )
        {
            *max = i;
        }
    }
}

int main(void) 
{
    size_t n = 1;

    printf( "Input the number of elements to be stored in the array: " );
    scanf( "%zu", &n );

    int a[n];

    srand( ( unsigned int )time( NULL ) );

    for ( size_t i = 0; i < n; i++ )
    {
        a[i] = rand() % ( int )n;
    }

    for ( size_t i = 0; i < n; i++ )
    {
        printf( "%d ", a[i] );
    }
    putchar( '\n' );

    size_t min, max;

    minmax_element( a, n, &min, &max );

    printf( "The minimum value is %d at position %zu\n", a[min], min );
    printf( "The maximum value is %d at position %zu\n", a[max], max );

    return 0;
}

程序输出可能看起来像

Input the number of elements to be stored in the array: 10
2 0 4 2 4 3 0 9 1 0 
The minimum value is 0 at position 1
The maximum value is 9 at position 7

如何打印最大值和最小值的索引？

How do I print the index of the maximum and minimum values?

c

arrays

max

min

function-definition