程序代码：

#include <stdio.h>
#include <stdlib.h>

// 代替 fflush
// #define LINEEND while(getchar() != '\n')
#define LINEEND do{int ch; while((ch=getchar() != '\n') && ch != EOF)}while(0)

// 自定义函数解决
// myGetLine(clientName, sizeof clientName);
int myGetLine(char *str, int size)
{
    int ch, i;
    
    if (!str || size < 1)
        return 0;

    for (--size, i=0; (ch=getchar() != '\n') && ch != EOF && i < size; ++i)
        str[i] = ch;
    str[i] = '\0';
    
    while(ch != '\n' && ch != EOF)
        ch = getchar();
    return i;
}


int main(void)
{
    char clientName[21];
    char input[1024];
    printf("please input your name,note:your name lenth not over 20 byte\n");
    scanf("%s",clientName);
    fflush(stdin); // LINEEND;
    while(1)
    {
       fgets(input, sizeof(input), stdin);
       fflush(stdin); // LINEEND;
       break;
    }
    
    puts(clientName);
    puts(input);
    return 0;
}

程序代码：

    printf("please input your name,note:your name lenth not over 20 byte\n");
    scanf("%s",clientName);
    if(send(sd,&clientName,strlen(clientName),0)<0)
    {
       perror("send");
       exit(1);
    }
    if(pthread_create(&pd,NULL,(void *)dellMsgFromServer,sd)!=0)
    {
       perror("pthread_create");
       exit(1);
    }
    while(1)
    {
       input[0]='\0';
       fgets(input,1024,stdin);
       input[strlen(input)-1]='\0';
       if(send(sd,&input,strlen(input),0)<0)
       {
          perror("send");
          exit(1);
       }