c语音解答，可以有偿

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#include<stdio.h>

int main() {
    int n;
    FILE *fp;
    char c;

    printf("---------------菜单-------------\n");
    printf("a)找到data.txt中的最大数字\n");
    printf("b)计算data.txt中所有正数的平均值\n");
    printf("请选择a或b：");
    c = getchar();
    if (c=='a' || c=='A')
    {
        int max;
        fp = fopen("data.txt", "r");
        fscanf(fp, "%d", &max);
        while (fscanf(fp, "%d", &n)>0)
        {
            if (n>max)
                max = n;
        }
        fclose(fp);
        printf("最大数字:%d",max);
    }
    else
    {
        float sum=0,avg;
        int i=0;
        fp = fopen("data.txt", "r");
        while (fscanf(fp, "%d", &n)>0)
        {
            if (n>0) {
                sum += n;
                i++;
            }
        }
        avg = sum/i;
        fclose(fp);
        printf("所有正数的平均值%.3f",avg);
    }

    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char *ReadFile(char *path, int *length)
{
    FILE *pfile;
    char *data;

    pfile = fopen(path, "r"); //open as binary
    if (pfile == NULL)
    {
        return NULL;
    }
    fseek(pfile, 0, SEEK_END); //读取文件长度
    *length = ftell(pfile);
    data = (char *)malloc((*length + 1) * sizeof(char));
    rewind(pfile);
    *length = fread(data, 1, *length, pfile);
    data[*length] = '\0';
    fclose(pfile);
    return data;
}
int main(int argc, char const *argv[])
{
    char *content;
    int data[20] = {0};
    int count = 0;
    int length;
    // char *path = "./input.txt";4
    char *path = "F:\\Ctest\\input.txt";
    char *p;

    content = ReadFile(path, &length); //字符串形式的input内容
    p = strtok(content, " ");          //初次分割
    while (p)
    {
        data[count] = atoi(p);
        // printf("%d\n",data[count]); 此模块已经写好，现在data的前16项为对应数字了
        ++count;
        p = p = strtok(NULL, " "); //继续分割
    }
  //  printf("%d\n", count);
    int choice;
    printf("enter 1 for mode 3a;\nenter 2 for mode 3b.\n");
    scanf("%d", &choice);
    switch (choice)
    {
    case 1:
    {
        int max = data[0];
        for (int i = 1; i < count; i++)
        {
            if (data[i] > max)
            {
                max = data[i];
            }
        }
        printf("max number in txt is %d.\n", max);

        break;
    }
    case 2:
    {
        float average = 0.0;
        int positive_count = 0;
        for (int i = 0; i < count; i++)
        {

            if (data[i] > 0)
            {
                positive_count++;
                average += data[i];
            }
        }
        average /= positive_count;
        printf("the average number of all positive numbers is %f\n", average);
    }
    break;
    default:
    printf("Invalid option!\n");
        break;
    }
    return 0;
}