c语言问题。这个实在不会写

Question

Write a program that reads from a text file named "messages.txt" line by line (until end-of-file,EOF) and echoes the messages to the display.
Have the program recognize and implement the following command-line arguments:

多谢，实在不知道怎么写

Answer 1

英文看不大明白，这个命令行参数是cmd窗口中输入的命令行参数么？

#include <stdio.h>
int main(int args,char *argv[])
{
    FILE *fp = NULL;
    int i=0,n=0,m=0;
    char buf[1000];
    char word[100][20] = {0};

    if(args < 2)
    {
        printf("参数不足");
        return 0;
    }
    fp = fopen(argv[1],"r");
    if(fp == NULL)
    {
        printf("文件打开失败.");
        return 0;
    }
    while(fgets(buf,1000,fp) != NULL)
    {
        for(i=0;i<100;i++)
            memset(word[i],0,20);
        i=0;
        n=0;
        m=0;
        if(args == 2)
            printf("%s\n",buf);
        else
        {
            if(argv[2][1] == 'u')
            {
                while(buf[i] != '\0')
                {
                      if(buf[i]>='a' && buf[i] <='z')
                          printf("%c",buf[i] - 32);
                      else
                          printf("%c",buf[i]);
                      i++;
                }
            }
            else if(argv[2][1] == 'l')
            {
                while(buf[i] != '\0')
                {
                      if(buf[i]>='A' && buf[i] <='Z')
                          printf("%c",buf[i] + 32);
                      else
                          printf("%c",buf[i]);
                      i++;
                }
            }
            else if(argv[2][1] == 'r')
            {
                 while(buf[i] != '\0')
                {
                    if(buf[i] == '\n')
                    {
                        i++;
                        continue;
                    }
                      if(buf[i] == ' ')
                      {
                            if(m!=0)
                                n++;
                            m=0;
                      }
                      else
                          word[n][m++] = buf[i];
                      i++;
                }
                 if(m!=0)
                     n++;
                for(i=n-1;i>=0;i--)
                    printf("%s ",word[i]);
            }
        }
        printf("\n");
    }
    fclose(fp);
    return 0;
}