程序代码：

#include <stdio.h>

int main(void)
{
    float a[100];
    int i = 0;
    int n;
    float max;

    while (1)
    {
        printf("Enter a number: ");
        scanf("%f", &a[i]);

        if (a[i] <= 0)
        {
            break;
        }
        i++;
    }
   

    max = a[0];

    for (n = 1; n <= i; n++)
    {
        if (a[n] > max)
        {
            max = a[n];
        }
    }
    printf("The largest number enter is: %f\n", max);

    return 0;
}

程序代码：

#include <stdio.h>

int main( void )
{
    double maxval = 0.0;

    for( double val;  printf("Enter a number: "), scanf("%lf",&val)==1 && val>0; )
        if( maxval < val )
            maxval = val;

    printf( "The largest number entered was %f\n", maxval );

    return 0;
}