stdin,stdout,stderr,fscanf,fprintf

fprintf:file printf：把输出写入到文件中

fscanf:file scanf：从文件中读取数据

sprintf(char a[ ],),sscanf(char a[ ],)

fprintf(FILE*,),sscanf(FILE*,)

C语言为我们定义了三个现成的FILE*指针:stdin stdout stderr

stdin：标准输出文件/设备  fflush(stdin)：清空缓冲区，不可靠

stdout：标准输入文件/设备  flush(stdout)： 刷新标准输出文件

stderr：标准错误文件

#include

int main()
{
    fprintf(stdout,"input name age weight:");//输出到屏幕

    char name[10];
    int age;
    float weight;
    fscanf(stdin,"%s %d %f",name,&age,&weight);//从键盘读
    fprintf(stdout,"%s is %d years old,%gkgn",name,age,weight);
    
    

    return 0;
}

#include

int main()
{
    char name[10];
    int age;
    float weight;

    FILE* rfp = fopen("./in","r");
    if(rfp==NULL)
    {
        printf("error readn");
        return 1;
    }
    fscanf(rfp,"%s %d %f",name,&age,&weight);//read from file
    printf("%s is %d years old,%gkgn",name,age,weight);
    fclose(rfp);


    FILE* wfp = fopen("./out","w");
    if(wfp==NULL)
    {
        printf("error openn");
        return 2;
    }
    printf("write to file!n");
    fprintf(wfp,"%s is %d years old,%gkgn",name,age,weight);//write to file
    fclose(wfp);

    return 0;
}