putchar输出错误

#include<stdio.h>
#include<stdlib.h>
int main(int argc, char *argv[])
{
        int get_char = 0;
        char s[20] = "i love linux!";
        FILE *fd;
        if(argc < 2)
        { printf("please input pathname!\n");
                exit(1);
        }
        if((fd = fopen(argv[1],"w+")) == NULL)
        {
                printf("open failure!\n");
                exit(1);
        }
        while(get_char != EOF)
        {
              putchar(get_char);      // 1

              get_char = fgetc(fd);// 2  将1 和 2 交换会出现一个小错误
                
        }
        fclose(fd);
        return 0;
}