如何创建 C 程序以通过输入的值确定最大数字？

Question

我创建了一个程序来确定最大数，但我的讲师说它并不完美，有人可以让它完美吗？

 #include <stdio.h>
 int main () {
     double a,b=0,n, i;
     printf("limit of n input: ");
     scanf ("%lf",&n);

     for (i=1;i<=n;i++) {
         scanf("%lf",&a);
         if (a>b) b=a;
     }

     printf("%.2lf", b);

     return 0;
 }

Answer 1

如果她所说的“不完美”是指“不能正确处理负数或空集”，那么你会想要

1. 将 n
2. 读取循环外的第一个数字，因此您不会对可能的最小数字做出假设

Answer 2

我会这样做，对于大量的文字感到抱歉。我认为它来自典型的 Objective-C 风格的长词编程：

#include <stdio.h>

int clean_stdin() {
    while (getchar()!='\n');

    return 1;
}

int main(int argc, char *argv[]) {
    char c;
    signed int count = 0;    // number of numbers to scan

    unsigned int fireErrorMessage = 0;
    do {
        if (fireErrorMessage == 1) {
            printf("You entered not a positive natural number. Please enter a number >0 Examples: 1 22 4012\n"); // output for the user
        }
        if (fireErrorMessage == 0) {
            fireErrorMessage = 1;
        }
        printf("How many integers do you want to insert (Inser a number >0)? ");
    } while (((scanf("%d%c", &count, &c) != 2 || c != '\n') && clean_stdin()) || count < 1);

    signed int indexOfNumber; // for index, declared outside because of output at the end

    signed int highestNumberIndex;
    double highestNumber; // saving the highest value in a helper variable

    fireErrorMessage = 0;
    for (indexOfNumber = 1; indexOfNumber <= count; indexOfNumber++) {
        double scannedNumber;
        do {
            if (fireErrorMessage == 1) {
                printf("You entered not a number. Please enter a number. Examples: 3.0 -1 14\n"); // output for the user
            }
            if (fireErrorMessage == 0) {
                fireErrorMessage = 1;
            }
            printf("Input number %d: ", indexOfNumber); // output for the user
        } while (((scanf("%lf%c", &scannedNumber, &c) != 2 || c != '\n') && clean_stdin()));

        fireErrorMessage = 0;

        if (indexOfNumber == 1 || scannedNumber > highestNumber) {
            highestNumberIndex = indexOfNumber;
            highestNumber = scannedNumber;
        }
    }

    printf("Highest input number on index %d, the value is about %.2lf\n", highestNumberIndex, highestNumber);

    return 0;
}

输出

How many integers do you want to insert (Inser a number >0)? aa5
You entered not a positive natural number. Please enter a number >0 Examples: 1 22 4012
How many integers do you want to insert (Inser a number >0)? -3
You entered not a positive natural number. Please enter a number >0 Examples: 1 22 4012
How many integers do you want to insert (Inser a number >0)? 3
Input number 1: aa
You entered not a number. Please enter a number. Examples: 3.0 -1 14
Input number 1: -50.0001
Input number 2: 51a
You entered not a number. Please enter a number. Examples: 3.0 -1 14
Input number 2: -1.00
Input number 3: -0.1
Highest input number on index 3, the value is about -0.10

Answer 3

此代码适用于循环索引的负数而非数字输入以及循环内的负数而非数字输入。谢谢

  #include <stdio.h>
  #include <math.h>
  int main () {
             int n, i;
             double a,b=0;
             printf("limit of n input: ");
             scanf ("%lf",&n);

            if(n < 0){
                      printf("value of n cannot be negative");
                      return 0;
                     }
           else if (n == 0)
                     return 0;
           else if (isnan(n))
                     return 0;

           else{
             for (i=1;i<=n;i++) 
               {
                   scanf("%lf",&a);
                   if(!isnan(a) && a > 0)
                         { 
                          if (a>b) b=a;
                         }

               }
              printf("%.2lf", b);

              return 0;
               }
             }